IAEA-TECDOC-845

Nuclear techniques coalinthe industry

Proceedings finala of Research Co-ordination Meeting held in Krakow, Poland, 9-12 May 1994

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NUCLEAR TECHNIQUES IN THE COAL INDUSTRY IAEA, VIENNA, 1995 IAEA-TECDOC-845 ISSN 1011-4289 IAEA© , 1995 Printed by the IAEA in Austria November 1995 FOREWORD

e yearlasw fe Th t s have witnessed many important advance e developmenth n i s d an t application nucleaf so r technique coae th l n sindustryi . Nuclear borehole logging techniques basen do measurement of natural radioactivity, X and gamma ray absorption and scattering and neutron interactions are extensively employed for exploration programmes and in situ evaluation of coal.

On-line analysis based on a variety of techniques is widely used to optimize coal processing operations increasee th ; d product yiel assuref do d qualit reductiod yan energn ni y usage have resulted in enormous economic benefits to the coal industry. Further, the potential of nuclear techniques for control and minimization of environmental pollution in the various stages of exploration and exploitation of coal are increasingly being recognized and much work is under way to develop and apply such technique coan si l processing operations.

With the aim of promoting advanced research and facilitating a more extensive application of nuclear technique environmentar sfo l protectio exploratioe th n i exploitatiod nan coalf n o IAEe th , A establishe e presendth t co-ordinated research programme (CRP 1989n i ) . This report includen sa assessment of the current status and trends in nuclear techniques in the coal industry and the results obtaine participante th y d b CRPe th t sa . Proceeding "Nuclean o P finae th CR lf r o sTechnique n i s Exploratio d Exploitatioan n f Coalo n : On-lin Buld an ek Analysi d Evaluatioan s f Potentiao n l Environmental Pollutants in Coal and Coke", was held in Krakow, Poland, from 9 to 12 May 1994.

The IAEA wishes to thank all the scientists who contributed to the progress of this CRP. PLEASE BE AWARE THAT MISSINE TH AL F LO G PAGE THIN SI S DOCUMENT WERE ORIGINALLY BLANK EDITORIAL NOTE

In preparing this publication for press, staff of the IAEA have made up the pages from the original manuscripts submittedas authors.the viewsby The expressed necessarilynot do reflect those governmentsofthe nominatingthe of Member nominating the States of or organizations. Throughout the text names of Member States are retained as they were when the text was compiled. The use of particular designations of countries or territories does not imply any judgement by publisher,the legalthe IAEA,to the status as of such countries territories,or of their authoritiesand institutions delimitation ofthe or of their boundaries. The mention of names of specific companies productsor (whether indicatednot or registered)as does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement recommendationor partthe IAEA. ofon the The authors are responsible for having obtained the necessary permission for the IAEA to reproduce, translate or use material from sources already protected by copyrights. CONTENTS

1. SUMMARY ...... 7

1.1. Result IAEA'e th f so s Co-ordinated Research Programme ...... 7 . 1.2. Nuclear borehole logging techniques ...... 8 . 1.3. On-line analysis ...... 8 . 1.4. Ash monitors ...... 8 1.5. Gamma transmission gauge ...... 9 . 1.6. Measurement of calorific value ...... 9 1.7. Natural radioactivity and neutron activation ...... 9 backscatteriny ra 1.8X . g techniques ...... 0 1 . 1.9. Nuclear technique coar embeddind sfo an l g rocks ...... 0 1 . 1.10. Conculsion recommendationd san P ...... CR e th f so 1 1 .

2. ASSESSMEN NUCLEAF TO R TECHNIQUE COAE TH LN SI INDUSTR Y .....1 1 .

2.1. Exploration ...... 11 2.2. Mining ...... 2 1 . 2.3. On-line analysi f coa sprocesr o fo l s control ...... 2 1 . 2.4. Utilisation of coal ...... 14

COUNTRY REPORTS

On-line analysi coaf so powe n i l r generation ...... 7 1 . N.G. Gutmore, M.L. Mitten, B.D. Sowerby Nuclear borehole logging techniques for coal quality ...... 45 orsB am M. Typical case f applicatioso isotope th monitorf h no e as Chinn si a ...... 5 5 . HongchangY. Desig constructiod nan f gammno a transmission gaug determinatior efo h as e th f no content in coal ...... 65 A. Abedinzadeh, H. Rahimi, N. Rahimi, J. Moafian, A. Amini, A. Baniscdam Effects of humidity changes on the measured calorific value of coals ...... 79 T. Cywicka-Jakiel, J. Loskiewicz , G.Tracz Coal ash parameters by natural radioactivity and neutron activation ...... 99 E. Chrusciel, S. Kali to, J.L. Makhabane, A. Lenda, N guy en Dinh Chan, J.W. Ntewodniczanski, PalkaK. Application of X-ray backscattering techniques on Turkish coal analysis ...... 109 P. Arikan, A. Zararsiz, R. Kirmaz, N. Efe Application of nuclear techniques for analysis of Vietnamese coal and embedding rocks .... 131 Vo Doc Bang, Phcon Van Duong, Nguyen Thanh Binh. Le Tien Quan, N guy en Manh Hung, Nguyen Thi Hong, Vo Hoang Lam

Lis Participantf o t s ...... 5 14 . 1. SUMMARY

Coa majoa s i l r energy sourc foreseeable worldwidth n i expectes o i s d e b ean future o dt . Annual coal production in 1991 was almost 4425 million tonnes per year. Several developing countries are rapidly increasing their production.

energn f coaa o s Tha e ly eus sourc severs eha e environmental consequences emissioe Th . n of ash causes fall-out which discolours houses and the ground, and poses potential threats to plants, animals, and human life. The emission of SO causes acid rain which threatens to kill the forests

and causes extensive damag buildingo et s throug corrodins hit 2 g effect.

Based on such environmental reasons, in addition to economic considerations, the efficient use sulphuw lo f o r coabecoms ha l majoea r energy issue.

Nuclear measurement techniques can be efficiently used to monitor different components in coae th l affectin efficienenvironmentas d git an e us t l effects. Recent years have see nrapia d expansion of research into, and industrial application of, nuclear techniques for the on-line and bulk analysis of coal and coke. The main application areas of nuclear techniques in the coal industry are determinations of ash, moisture and specific energy of coal, determinations of solids weight fraction contenh anas d f coa o t slurries n determinatioe i l th d an , concentratione th f no f specifiso c elements suc sulphus ha radioactivd an r e pollutant morr o f these coaln eo si On e. determination usee sar o dt control mining operations, coal preparation, and power stations.

promotinf o m Witai e ghth advanced researc facilitatind han morga e extensive applicatiof no nuclear techniques for environmental protection in the exploration and exploitation of coal, the IAEA established a Co-ordinated Research Programme (CRP) in 1989 on the Use of Nuclear Techniques in the Coal Industry. This report includes an assessment of nuclear techniques in the coal industry and the results obtained by the participants of the CRP.

contributo t objective s efforte Th wa th P f o thiet seo sCR toward s developmen wided an t r applications of nuclear techniques with a view to minimizing the release of environmental pollutants stage e exploratioe th th l in sal i exploitatiod nan coalf participatinne o Th . g groups concentrated their research efforts on evaluation of improved nuclear bore hole logging techniques for coal quality, on- line analysis technique systemsd san , evaluatio f low-cosno t isotop monitorinh eas g techniquer sfo evaluatio f potentiano l environmental pollutant coacoken d i s an l . Wherever possible researce th , h wor orientes kwa d toward developmene sth f techniqueo t s suitabl r adoptioefo locao nt l conditions prevailing in developing Member States.

1.1. RESULTS OF THE IAEA'S CO-ORDINATED RESEARCH PROGRAMME

Research contracts and research agreements were concluded with scientists from Australia, China Islamie th , c Republi f Iranco , Poland, Turke Vied yan t Nam. Three Research Co-ordination Meetings were held - 1991 Bandung, Indonesia; 1992 Ankara, Turkey and 1994 Krakow, Poland.

maie Th n achievement havP eCR beee followinge th nth f so :

Two techniques for coal logging have been extensively evaluated in Australia, namely: spectrometrie th ) (a c gamma-gamma metho determinatior dfo contenth as e d th an ,f no prompe th t neutron-gamm) (b a metho determinatioe th r dfo f ashno , calorifin i e cF valued an i S , coal.

Further, a number of on-line analysis systems for use in coal-fired power stations have been developed. These include system on-line th r sfo e analysi ranw lo k f coalso , unburnh t as carbo y fl n ni and pulverized coal mass flow. These systems utilize nuclear, microwav ultrasonid ean c techniques. A technique inelastie baseth n do c scatterin neutronf go carbonn C so 12 ) y , namelyn' , (n C 12 , with 4434 keV gamma rays produced with a cross-section of 0.15 to 0.35 barns, has been delineated for evaluating the calorific value and the ash content of Polish coals. Low cost coal ash gauges based on the attenuation of soft gamma radiation have been developed in Viet Nam and China and their performanc bees eha n evaluated. Considerable progres bees sha n maddesige inexpensivn th a n ef i n o e dual energy gamma ray transmission gauge in Iran for use in low throughput mines.

Natural gamma ray spectrometric and neutron activation techniques have been employed in Polan identifo dt y lithology, determin thicknese eth carboniferouf so s layers separato ,t e dirt band from coal during exploitatio processingd nan localizatior fo d an , coaf no l seam wela s sa l logging method. naturae Th l gamma spectrometric metho bees dha n founadequate b o dt quantitativr efo e determination of the ash content, calorific value and carbon content of Polish coals. Scattering of X rays and XRF backscattering have been used in Turkey to determine ash content, mineral matter and sulphur in coals.

1.2. NUCLEAR BOREHOLE LOGGING TECHNIQUES

techniqueo Tw s have been develope Australin di a ove pase th r t decad r coaefo l logginn gi boreholes:

(1) the spectrometric gamma-gamma technique for the determination of ash content in coal; prompe th t gamm) (2 a neutron activation (PGNA) techniqu determinatioe th r efo ashf no , caloric value, Si and Fe in coal.

A comparison betwee gamma-gamme nth neutron-gammd aan a technique predictioh as r sfo n in water filled quality control boreholes of 140 mm showed that the neutron-gamma technique was superio predictinn ri contenh coae as th e lf gth seamsto , whic higd hha h variatio contente F n e ni Th . neutron-gamma technique is superior because it can also determine the Si and Fe content of coal and it can sample a larger volume of coal.

1.3. ON-LINE ANALYSIS

The on-line analysis techniques developed in Australia include nuclear, microwave and ultrasonic techniques. The nuclear techniques are used for the determination of moisture, ash, gross wet specific energy and sodium/ash ratio, whereas the microwave techniques are used as an independent means of determining moisture. The first commercial gauge based on these techniques was installed at a power station in 1993. Ultrasonic and microwave techniques for measurement of

coal mass flow have been developed and evaluated on a pilot scale recirculating dust rig. Among

238 nuclear techniques, PGNA Am-BbasePu-B 241 n do r eo detectoe O e mossourcth BG s td i r an e effective, accurat reliabld ean e technique.

MONITORH 1.4AS . S

Four types of ash monitors are in use in China:

(1) off-line application of the ZTHY Intelligent Isotope Ash Monitor; Monitoh As Y coan i r FH l preparatio ) (2 n plant powed san r stations, l on-linZ- e automati) (3 c rapid calorimeterd an ; ) (4 BHZ-1 prototype portable laboratory-size Intelligent Isotop h MonitoAs e s beeha r n successfully applied in coal washing, coking, and power sectors to meet to a certain extent the requiremen rapin o t d determinatio f coano l ash.

Currently some 40 of such monitors are in use, bringing about remarkable economic and social benefits. 1.5. GAMMA TRANSMISSION GAUGE

More then two years research work carried out in the Islamic Republic of Iran on design of a dual energy gamma ray transmission gauge has been reviewed. The gauge after construction can installee b coae th l n di industr thao ys t coal transporte conveyoa n do rnona beln i -te whicb y hma homogeneous mixtur r moreo froe e mevaluatede on mineb n sca . Therefore, prio gaugo rt e design, primary investigation is done to identify and evaluate the relationship between the mass absorption coefficient and ash percent of coal for the mixture running on the belt. Results of investigation show that coal mixture calibration curves cannot be used accurately for ash estimation in coal of individual mines and, essentially gauge wory ,th determineo kma t percenh as e eth t with some limitation thin si s particular region. Therefore, the design of gauge was carried out in the laboratory and, after setting up, the primary experimental calibration curve for the gauge was obtained. It is planned to develop prototypa industriaf eo neae th monito h r n teso i futureas t l t i td an r .

1.6. MEASUREMENT OF CALORIFIC VALUE

calorifie Th c valu inferree b coaf en o differeny ca ldb t instrumental techniques simplese Th . t is to measure the ash content of the coal and use the evident link: low ash - high calorific value, high calorifiw lo - ch as values possibli t I . prompe e us als o ot t neutron-gamma activation analysis registering gamma ray from radioactive capture on carbon. Here the cross-section is quite low for this

reaction. When using high energy neutrons from Pu-Be or Am-Be sources one can take advantage

12 of the inelastic scattering of neutrons on carboCn12 (n, n', y)C with 4434 keV gamma rays produced.

Investigations were carried out in Poland on:

correlatioe th (1) n betwee contenth nas , carbon conten calorifid an t c valu f coaleo ; (2) calculations of the influence of moisture content of 4.43 MeV carbon gamma-ray signal yield for different source detector spacings; experimentae th ) (3 l data concernin change gth carbof eo n gamma-ray signal with rising moisture; (4) the use of a hydrogen signal in correcting the carbon concentration from 12C (n, n', y)12C reactio coaln ni d an ; (5) possibilities of registering other elements in coal using Pu-Be neutron source.

1.7. NATURAL RADIOACTIVITY AND NEUTRON ACTIVATION

Natural radioactivit coa0 sedimentard 40 an l f yo y rock samples collected from well coren si Poland has been measured in order to determine the uranium, thorium and potassium concentrations with the use of a scintillation gamma ray spectrometric system. The determined concentrations were used to identify the lithology of the rocks and evaluate the following hard coal parameters: ash content, calorific valu carbod ean n content.

Experimental investigations carriePolann i t f naturadou do l gamm spectry ara a have shown that quantitative determinatio contenth as e th ,f ncalorifio c valu carbod ean n conten naturay tb l gamma ray spectrometr feasibles ywa .

Natural gamma ray measurements of the carboniferous rocks have shown that the specific activit f shaly o mudston d ean highes ei r than tha f bituminouto s coal. These observation usee b dn sca identifo t y lithology determino t , thicknese eth carboniferoue th f so s separatlayero t d san e dirt bands from coal during exploitatio processingd nan .

The natural gamma ray log is relatively simple, fast, inexpensive and more attractive than any other nuclear method since it does not require application of radioactive sources.

The neutron activation technique proved to be useful for rapid assays of coal samples and for localization of coal seams as a well logging method. The obtained results demonstrate feasibility of determination of the coal ash parameters: ash content in coal and ash fusion temperature by the neutron activation method, both in laboratory and through borehole logging lattee .Th r application enable geologiste sth determino st e parameter coaf so l as the industrial fuel at the early stage of evaluation of a coal deposit.

BACKSCATTERINY RA 1.8 X . G TECHNIQUES

coae Inth l industr Turken yi y non-nuclear methodbeinw no g e usesar d whic highle har y time consuming. There is a considerable demand for a rapid and sensitive method of monitoring coal ash not only in the coal industry but also for power stations and the steel industry.

One of the requirements concerning analysis technique of ash in coal is that it should be rapid, have adequate sensitivity and simple sample preparation. The technique described in the work was developed primaril meeo yt t these requirements.

idee fluorescency f applyinTh ao ra X e gth e (XRF) techniqu contenh as analyso e t e th t f eo of coal is not new. A wide range of procedures have been detailed during the last decades for studies of coal in this way.

The application procedures of nuclear techniques in exploration, mining and coal preparation, in particular revieweds wa , .

fluorescency Xra e method using backscatterin determinatioe th r gdomestin fo i h as f nco coals was studied in their as-received forms. Fluorescent intensities from major content of mineral matter , singl Fe theid , yan Ti r , combinationsucCa s ha s were employe conjunction di n wit reciprocae hth l of the backscattering intensity in an empirical relationship.

The X ray backscattering method using some assumptions and expressions has been applied to determination of ash percent, sulphur content and calorific value in coal. About seventy coal samples were analyze proposee th y db d method.

As a result of the improvement in experiments mentioned, ash monitors were designed in order to test some domestic samples in the laboratory. Analysis of these samples gave results which were in excellent agreement wite expecteth h d value d verifiean s e suitabilitth d f thio y s calibration procedure for determining of qualification of coal. The calibration demonstrates the validity of this procedure for samples of varying mineral matter, mostly iron content, because compensation for XRF essentias i e F r estimatiof fractionh o fo l as e th .f no

Disadvantage of method is limited particle size acceptance, but use of higher energies or fine grinding of sample could overcome this trouble. Work to standardise an ash monitor for field use is in progress.

1.9. NUCLEAR TECHNIQUES FOR ANALYSIS OF COAL AND EMBEDDING ROCKS

Determinatio f elementano l compositio f anthraciteno , coaembedded an l d rock beed ha sn carried out in Viet Nam by nuclear analytical techniques. Concentrations of up to 26 elements in coal and rocks were investigated. These data could be useful for evaluation of potential hazard of using coal as a fuel for coal fired power plants and coal ash for construction material fabrication. They also coul usefue db r geochemicafo l l investigation.

Investigatio naturae th f no l radioactive elements concentratio anthracitw ra n i e coa shows lha n that there was weak correlation between their concentration and ash values. The reason for this phenomeno explaines nwa d eithe "unrelatedy b r " coal seamspeciay b r so l geological procese th f so anthracite coal basin formation. In any case, it appeared that more detailed investigations were needed for full resolution of the problem.

10 simplA gaugh eas e that could measur iroe eth n content variatio constructes wa coan nh i as l d as the first step towards the application of nucleonic control systems in the coal industry.

1.10. CONCLUSIONS AND RECOMMENDATIONS OF THE CRP

With the rapidly growing use of coal in many developing countries and the increasing awarenes environmentas it f so l impact rolscope d th ,e an f nuclea eo r technique coae th l n si industr y an coan di l power generatio wele nar l recognized.

reaffirmeP CR e Th d that nucleonic control system (NCS) unit on-linr sfo e coal processine gar commercially produce wideld dan y use mann di y advanced countries with great benefit. These are, however t quit n no lowi , ee - suiteus throughpu r fo d t coal mine therd an ss muci e h scopr fo e development and use of portable low-cost NCS units for such use. NCS units based on natural radioactivity (as against using strong external radiation sources), and logging tools based on gamma - gamma method micra d soan gamma source mucf o e har , interes vien ti theif wo r verradiatiow ylo n hazard. Further, the CRP found that there is considerable scope for regional co-operation among countries in such efforts, as well as for greater global co-operation to stimulate the transfer of these technologies.

The following recommendations were made at the conclusion of the programme:

(1) At the international level, more technical assistance projects should be supported in areas of low-cost NCS, improved borehole logging tools theid an , r evaluation. neede lighn th I f so t identifie programme'e ) th (2 d dan s economi environmentad can l relevance, further researc requireds hi , preferably throug mechanise hth CRPa f mo .

(3) Participants recommended that the further research much cover both coal and metal mining industries, since techniquee somth f eo s develope relevane dar boto t h industries.

. ASSESSMEN2 NUCLEAF TO R TECHNIQUE COAE TH LSN I INDUSTR Y

In coal mining and utilization there are four distinct stages, where quality control of coal is important:

) (1 Exploration: findin delineatind gan coae gth l deposit. (2) Mining: getting the coal out of the ground in the most efficient way. (3) On-line analysis of coal for process control. ) (4 Utilizatio f coalno .

2.1. EXPLORATION

Nuclear borehole logging technique importane sar exploratioe th t ta n stage mose Th .t common borehole logging technique is based on the backscattered gamma radiation (gamma-gamma). In this technique the formation is irradiated with gamma radiation of initial energy below the pair production threshold (1.02 MeV) scatteree th ; d radiation returnin sonde th o get (detector system) with energy well above the photoelectric absorption region (say 150 keV) is detected. There is a simple relationship betwee electroe nth n densit hencd ybulan e eth k densit formatioe counth e f th y o d t ratnan e recorded; bule th k density characterize mineralogye sth .

A density logging sonde has a 137Cs source and a gamma ray detector which is well shielded gammV ke 2 froa source e 66 raym th e 137f s o belo Ce Th .sar threshole wth pair dfo r productiod nan insensitive to significant photoelectric absorption. The ash content of the coal can be estimated from correlatioe th n betwee contenth densite nas th d yan .

11 The spectrometric gamma-gamma techniqu latea s ei r developmen late th e n 1980s(i t d an ) involve sitn i s u spectrometr restrictea n yi d sense, i.e. some energy selectio performes ni e th n o d detected gamma rays. The most common method is to measure the ratio between count rates recorded broao intw d spectral window energiesw lo t higgamma-gamme sa d Th han . a techniqu uses ei o dt delineat coae eth l seam determind san e their thicknes deptd san h unde surfacee rth determinatio e Th . n of the ash content of the coal seams is a new development in gamma-gamma logging.

Prompt neutron-gamma logging for coal is a later development in borehole logging (late 1980s). Analysis of the gamma spectra produced nearly instantaneously upon the capture of thermal neutrons can be used to evaluate elements such as chlorine, hydrogen, silicon, calcium, iron and sulphur.

The most common sources of radiation for prompt neutron-gamma logging are Am - Be, 252Cf or (d,t) accelerator source for neutrons. The gamma ray detectors used are Nal (Tl), Csl and BGO. Special high temperature, ruggedized photomultipliers are used to collect the light from the scintillator and produce an electronic pulse proportional to the incident gamma ray energy. Linear and digital electronic includee sar loggin e th n di g sond analyso et detectoe eth r output, contro stabilitys it l d an , when an accelerator is used, control its operation. For research purposes, a number of Ge semiconductor detector sondes have also been usedprompe Th . t neutron-gamma logging technique delineate coae sth l seams, measure contenh alsn as oca e coaf sdetermind th to an l calorifie eth c value and the Fe, Si and S content of coal.

2.2. MINING

Quality control hole drillee sar d during coal minin mann gi y ope minest ncu . These holee sar logged for coal quality (ash content, calorific value, Fe, Si, S content). Prompt neutron gamma logging techniqu s mori e e suitable thae gamma-gammth n a logging becaus t i providee s more information suc calorifis ha chemicach valuas d ean l composition.

apparens Ii t t that prompt neutron gamma technique latea s a ,r developmen coan i t l logging, will become more accepted by the coal mining industry. A neutron-gamma logging tool costs about

US $10 000 more than the gamma-gamma tool. The extra cost is due to the more expensive BGO detecto rneutron-gamm e useth n di more ath tooed expensivlan Cfe 252 neutro n source. Whe onle nth y information required is to delineate the coal seams and measure their ash content, gamma-gamma can be a better choice.

Bore logging tools based on the gamma-gamma technique, using a gamma-ray microsource are currently under development. These tools will find application in logging horizontal boreholes in underground mines. They will also be used in portable logging systems which do not require a dedicated logging vehicle.

2.3. ON-LINE ANALYSIS OF COAL FOR PROCESS CONTROL

maie Th n requirement analysie th r sfo f coa so l hav moisturd e an bee h nas e evaluationt bu ; increasingly an analysis of elemental composition is required. As environmental considerations become more important, analysis of elements such as carbon, sulphur and nitrogen would be required thus changin emphasie gth f gaugeso s require industriay db l users. The gauges availabl gauginh as rang a r e efo nucleaf g eus o r techniques, i.e.:

) (1 Natural radioactivity (2) X ray backscatter ) (3 Single gamm transmissioy ara n (4) Dual gamma ray transmission (5) Annihilation radiation (6) Neutron inelastic scatter, capture, activation.

12 The natural radioactivity of coal is due to the presence in it of K, U and Th. Generally, the coan i h l T reflect presencd an amoune sth K f eo f minera o t l admixtures (clay, shale) withi coae nth l sample; clean coals (low in ash) usually contain low concentrations of these elements. The concentration of C in coal linearly decreases with the increasing U content. These factors have been used to calculate the ash content, calorific value and carbon content of coal using the data on K, U and Th concentrations in coal.

gamme Th detectioy ara n system use measuro dt naturae eth l radioactivit f coayo l consists (Tll ) Na scintillatio" 3 x usuall" 3 a f yno crystal couple 102a o d4t channel pulse height analysern I . the scintillation spectrometric measurements the following three energy windows are used 1.36-1.54 MeV (K) 1.66-1.86 MeV (Bi, U series) and 2.4-2.8 MeV (Th series).

backscattey ra X e Th r techniqu principl e bases ei th n do e that whe materiana irradiates i l d with X rays, a portion of the radiation is absorbed and the remainder is reflected. The amount of absorption varies as per the average atomic number 'Z', the higher the atomic number of the sample, the greater the absorption. The variation of absorption with atomic number can be directly applied to the ash measurement since the ash forming elements Fe, Si, Al, S and P have, on the average, a higher atomic number than coal. These elements that constitute the ash reflect fewer X rays from a radioisotope source contenh . as Henc e coaf th o t moref s ei i l , more radiatio absorbes ni lesd ds an si reflecte detectore th o dt .

The detector system consists of a probe head, a measuring system and a mechanical feed system. The probe head consists of a pair of a8Pu sources and a X ray proportional counter arranged in a 'central-source geometry'. The signal from the proportional counter is taken and converted into percentageh as . Typically mechanicae th , l feed system consist samplea f so r takinfo r sample gth e fro maie mth n conveyo crushera beld an tdelive o rt measurinh as unifor ra e th o t mg m samplm 5 f eo unit at a rate of 16 kg per minute. After measurement of ash, the sample is again fed back into the main conveyo meany b rsecondar a f so y conveyor.

The single gamma ray transmission technique is again based on the correlation between the average atomic number 'Z' of the formation and the amount of radiation absorption. The higher the atomic number 'Z' the greater the absorption.

duae Th l energy gamma transmission (DUET) method depend determinatioe th n so e th f no intensities of narrow beam transmission of low and high energy gamma rays through coal on the conveyor. Both intensities depend on the mass per unit area of coal in the gamma ray beam and the low energy also depend e effectivth n o s e atomic numbe e f detectecoalo r Th . d intensitiee ar s determined separately by pulse height analysis of output pulses from the scintillation detector, and then combined to give an ash content of coal which is independent of the thickness and vertical segregation conveyoe coaf th o n o l r belt. DUET manufacture gaugew no e sar d commerciall Australin yi thed aan y have been describe detain di Wat y co-workerd b l an t severan i s l publications.

paie Th r production (PP) (also know annihilatios na n radiation) technique depende th n so measurement e intensitieth f so f gamma-rayso s back scattere coae resultind th an l y db g from pair productio Comptod nan n interactions. Both interactions depenbule th kn ddensito coale th e f th ;y o pair production also depend effective th n so e atomic numbe coalintensitiee e th Th f .bac e o r th kf so scattered gamma rays resultin interactiono g tw fro e mth separatele sar y determine pulsy db e height analysis of the output from the scintillation detector. The detected intensities are then combined to give the ash content. The main advantages of the PP gauge over the DUET gauge is that the PP gaug less ei s sensitiv variationo t facto) a composition4 h y f as e o (b r n gaugsi P P e e Th view. s coal streay b ina m taken fro maie mth n process line.gaugeP P coar sfo l manufactureanalysiw no e sar d commercially in Australia and have been described in detail by Watt and co-workers in several publications. The inelastic scattering of neutron on carbon i.e. 12C (n, n', y) 12C with 4434 keV gamma rays produced with a cross section of 0.15-0.350 barns has been used to measure the carbon

13 concentration, ash content and calorific value using the correlation between ash content, carbon content and calorific valu f coaeo l whic bees hha n represente severay db l empiric formulae.

Neutron activation has been found to be a useful technique for rapid assays of coal samples and evaluatio f coano l seam well-loggina s sa g method Pu-BA . e neutron sourc bees eha n used dan a multichannel spectrometer has been adopted to record gamma rays in 2 broad energy channels - the first one of a 300 keV width for the 843 keV gamma rays (of Mg created by neutron induced reactions Mn-84f o d gamma-rayV an 7i ke S d an I s A resultin , onMg g from activatio stablf no e isotope, Mn f so Fe and Co), and the second one of 500 keV for gamma rays from the 1780 keV region (gamma rays of Al-1779 keV resulting from activation of Al and Silicon isotopes, and those of Mn (1811 keV)). gooe Th d correlation found betweeprincipae contenh th as d e an nth t l constituent bees ha n h as f so utilised in the calculation. A Pu-Be source separated by a 1.5 m spacing from a 35 x 70 mm Nal (Tl) crystal has been used in the borehole evaluation.

Natural radioactivity techniques have been used mainl sortinr yfo g applications examplr fo , e differentiating between coal and rock in open cut mines. The X ray backscatter and the single gamma transmission technique limite e laboratorye sar th o dcoat e th ls a sampl, e mus carefulle b t y prepared for analysis. In the case of X ray technique the coal sample must be crushed and pressed. The other techniques have the possibility to be used on-line directly on a conveyor belt or on a sample by-line system. The dual energy gamma-ray technique is the most common on-line ash analysis technique. Lik l gammeal a technique accuracs sit limites yi elementay db l composition, particularly variation ni iron oxide. Ofte gauge nth e mus calibratee b t coar dfo l from different sources. Annihilation gauges potentially can be relatively more accurate, they have been used on sample by-line in a fixed geometry which favours the backscatter method. Use of this gauge has been limited due to difficulty in supply of high energy gamma sources required. Neutron gauges are beginning to take over from gamma gauge on-linr sfo analysih improveeo as t e sdu d accurac thet muce ybu y ar h more expensive compared to the other ash gauging techniques.

All these technologie wele ar s lcustomizee developeb n ca d r individuadan fo l coal types. The gauges are available in international market and several countries such as China and the Islamic Republi f Ira cdevelopino e nar theircoaln cosn w o glo e ow t. unitus r sfo

Ash determine gammy db techniquy ara limites ei elementay db l composition future th n eI . neutron gauges will take over, but at present gamma ray gauges are predominant because of lower cost, eas f installatioeo maintenanced nan .

2.4. UTILISATIO COAF NO L

Nucleonic on-line analysis gauges are used for monitoring and control of coal quality in coal- fired power stations. Nuclear technique e oftear s n use n suci d h utilitie n combinatioi s n with microwave, capacitance or ultrasonic techniques. The main coal quality parameters measured are moisture, ash sodiud an , m content sodiue Th . m conten significana s i t t factor influencin levee gth l foulinh as slaggin d f o gan boilersn gi neutroe Th . n inelastic scatter gamm techniquy ara employes ei d for these measurements and is described in the paper by Cutmore, Millen and Sowerby. This technique is also used to measure the carbon content of fly ash. Such measurements help to balance the burners and minimize losses of coal in coal-fired boilers.

14 COUNTRY REPORTS ON-LINE ANALYSIS OF COAL IN POWER GENERATION

N.G. CUTMORE, M.J. MILLEN, B.D. SOWERBY Division of Mineral and Process Engineering, Commonwealth Scientifi Industriad can l Research Organization, Menai, Australia

Abstract

The application of on-line analysis techniques in the mineral and energy industries opens up new possibilitie improvee th r sfo d contro f processeso l . Instea f manuao d l sampling followey b d laboratory analysis at a later time, rapid and accurate analyses can be provided in real time for improved control. As a result there has been a rapid increase in the industrial application of on-line analysis instrumentation ove lase rth t twenty years, particularl minerae th coan d yi an ll industries.

presene Th t paper describe developmene sth numbea f o t on-linf ro e analysis systeme us r sfo in coal-fired power stations with an emphasis on those systems using nuclear techniques. The first on-line analysi analysi se ran systew th r klo f fo coa mso s i l befor pulverises i t ei d prio combustiono rt . measuremene seconth e r Th fo mass de i th f s o tflo w rate pulverisef so transportes di t coai s e a l th o dt burners and the third is for the determination of unburnt carbon in the fly ash. The second and third systems have been developed primaril r poweyfo r stations burning black coals.

1. INTRODUCTION

The applicatio on-linf no e analysis technique minerae th energn sd i an l y industries openp su new possibilities for the improved control of processes. Instead of manual sampling followed by laboratory analysis at a later time, rapid and accurate analyses can be provided in real time for improved control. As a result there has been a rapid increase in the industrial applicatio f on-lino n e analysis instrumentation ove e lasth rt twenty years, particularl minerae th coan d yi an ll industries [1,2] CSIRe Th , O Divisio Mineraf no d an l Process Engineerin bees gha n actively involve thin di s field throug developmente hth , field testin commercialisatiod gan on-linf no e analysis systems. systemSome th f eo s developed by the CSIRO depend entirely on nuclear techniques; others use a combination of nuclear technique microwaved san , capacitance ultrasonir o , c techniques continuoue Th . s analysis and rapid response of these CSIRO systems has led to improved control of mining, processing and blending operations, with increased productivity valued at US$35 million per year to Australia, and US$65 million per year world wide.

The present paper describes the development of a number of on-line analysis systems for use in coal-fired power stations with an emphasis on those systems using nuclear techniques. The first on-line analysis system is for the analysis of low rank coal before it is pulverised prio combustioo t r measuremene nth secon e r [3]fo Th .mas e s di th sf o tflo w rates of pulverised coal as it is transported to the burners [4,5] and the third is for the determination of unburnt carbon in the fly ash [5]. The second and third systems have been developed primarily for power stations burning black coals.

17 2. ON-LINE ANALYSIS OF LOW RANK COAL

Backgroun1 2. d

Latrobe Th e Valley regio Victorin ni a contain sdeposia f approximatelo t y 200,000 million tonne soff so t brown coal. During 1990/91 approximatel millio6 y4 n tonne browf so n coal were produced from three open cut mines, situated at Yallourn, Morwell and Loy Yang; mor f thio es % thacoas use6 n9 wa ld directl r electricityfo y generatio minn ni e mouth power rankstationsw lo ,f coae wito s Th .i l h high moisture conten generalld h an tas w ylo contents. Typical properties of the Loy Yang coal are: moisture 57-66 %; ash 1-5 %(dry basis(db)); chlorine 0.04-0.54 %db grosd t specifian ; swe c energy 8-12 MJ/kg. Bote hth nitrogen and sulphur contents are generally low (<0.6%db) and no post-combustion emission reduction strategie requiree sar emissior dfo n control.

maie Th n coal quality parameter f interesso t include moisture, ashsodiud an , m contents. useable Th e energy conten coae th lf (net o specifit we t c energy strongls )i y influencey db moisture content e organith , c coa lcontenth propertieas e variatioA th . d san coa n ni l moisture content from 64% to 68% requires a 19% increase in the coal feed rate to provide same t heath ene t furnacee inputh o t t . Sodiu bees mha n demonstrate significana e b o dt t factor influencing the level of ash fouling and slagging in Latrobe Valley boilers. The transfer pricing arrangements between the open cut mines and power stations are based on t specifiwe t cne energe th y conten tonnagd tan e delivered.

r mosFo t practical application brown i s n coal power stations on-linn a , e analysis system should be able to meet the following requirements for accuracy: moisture content to within s received)(a % contenh wt as ;(dr5 % 0. withio yt twt basis(db))2 n0. ; specific energo yt withi MJ/kg3 n0. sodiud an ; m conten addition n withiI o t . importans i db n t i ,0.0 % 3wt t that the analysis system provide information in sufficient time for operators to react, powee th whether rfo statioe b t ri brinno t auxiliarn gi y burner flamr sfo e support initiato ;t e a more stringent water blowing/soot blowing regime to minimise ash fouling; or to control coae th l quality supplied, through managemen mai e coaw th nf ra l t o bunker inlet/outlet feed systems and the respective coal supply source(s). Generally, an analysis time of 15 minutes or less is required. Previous commercially available on-line analysis systems have been assessed for their applicability to Latrobe Valley brown coal analysis and each have some problems in meeting the above requirements for run-of-mine coal [1].

Option2 2. On-linr sfo e Analysis

Two distinct approaches to on-line analysis are firstly analysis directly on the conveyor belt and secondly analysis on a sample by-line. Direct on-belt analysis provides the advantages that a significant proportion of the coal is "seen" by the analyser, no sampling is required installatiod an generalls ni y simple cheaped an r r than sample by-line systems. However direct on-belt analysis require e analyseon s r coape r l stream (conveyoe b r n belt)ca t i ; affected by variability in loading (thickness) of material on the belt; and the analysis signals ma affectee yb rubbey db steel-cord ran conveyoe Yanth y f d o Lo powe gA e r th belt t r A . station, each of the two conveyors from the open cut bunker can carry coal at feed rates of up to 2500 tonne/hour. Normal operation is with only one conveyor, with a loading of

18 about 1900 tonne/hour e coa s crusheTh i .l e coao lesdt th sld thaan nm aboum 5 7 t thicknes. bele aboumm s th i t 0 n so 30 t

A by-line system could be based on the shaking tube principle in which movement of the coal throug tube h th ensure s ei boty db hvibratina g feeden bottoe a tub e th d t th ea ran mf o axial vibratio tube e Coalscae th f Th .n o n 450 900d 0an 0 analyser 225a lon e m y 0gsm us b diametem m 0 r30 tube constructed from filament-wound Kevla rpolyesten i fibr t ese r resin wit hwear-resistana t polyurethane lining bonde inside th o edt surfactubee th f . o e Coal flow rate is normally from 1 to 10 tonnes/h. The advantages of a by-line system are the abilit analyso yt e multiple feed stream providinf o d san g more accurate analyses becausf eo a well-characterise d uniforan d m geometry e maiTh .n disadvantage e costth ,e ar s complexit maintenancd yan samplina f eo g system.

Sample3 2. s

seto browf so Tw n coal samples fro Victoriae mth n Latrobe Valley were providee th y db State Electricity Commissio f Victorino a (SECV moisturer fo ) , ash, specific energd yan sodium measurements firse thesf o Th t. e sets (Se comprise) t1 sample4 d2 s from boty hLo Yan Yalloud gan m mines, weighing eachabou g secone k 0 Th .t 5 (Set dse consiste ) t2 f do Yany 12Lo g samples, approximatel eachg k 0 .y 4 Each sampl mixes riffle-splied wa dan o t t obtain approximately 400 g subsamples for moisture determination by CSER.O. Laboratory assay ashr sfo , sodium, chlorin specifid ean c energ Latrobe eacr th yfo f ho e Valley samples were provide SECVe th meae y rangd b Th . n an valuef eo eacr sfo h quantit f interesyo t are given in Table 1 for each of the two sets of samples. TABL . ESummar1 chemicaf yo l laboratory assaybrowe th f sno coal samples e useth n di present workmeae rangd Th f assayn an o .f eac o et s shownhse i s e rangth , e being indicate italicsy db .

Samplt ese f o . No Moisture Ash GWSE Sodium Chlorine (see test) samples () %ar (%db) (MJ/kg) (% db) (%db) 1 24 63.6 2.9 0.07 0.07 59.3-68.5 0.7-25.2 0.03-0. 1 8 0.01-0.16 2 12 62.7 1.9 9.7 0.18 0.16 60.7-65.2 0.6-3.1 8.9-10.8 0.03-0.49 0.05-10.8

2.4 Nuclear Techniques

2.4.1 Background

Prompt gamma-ray neutron analysis technique usee b determin o dt n sca concentratioe eth n f specifio c element coan si l with varying degree accuracyf so , dependin concentrationn go , inter-element interferences, neutron cross-sections, etc. Durin e 1980'g th earlie d san a r number of groups around the world carried out research and development into nuclear techniques for the on-line analysis of black coal. This work has led to a number of commercial gauges Gamma-metric,e sucth s ha Coalscae th d san n 9000 gauges, basen do ^Cf neutron sources and Nal(Tl) scintillation detectors in a transmission geometry. All these gauges analyse the coal as it passes down a vertical chute. The main advantage of

19 these gauge theis si r abilit measuro yt concentratione eth certaif so n specific elements such as sulphur, hydrogen, chlorine, silicon and iron. However these nuclear gauges do not give sufficient accurac ashr yfo , carbo r moisturno brown ei n coals.

CSER.O has been involved in assessing on-line analysis techniques for Victorian brown coal for a number of years. Correlations using Latrobe Valley coal have shown that it should be possibl determino et e moistur brown ei n coal base measurementn do carbone th f so , hydro- contenth coalas e d achievth o f T .an moisturs o % n accuracn ewt ge a 5 carbone 0. eth f yo , hydroge contenth as d nan s determine e neeb o dt withio dt respect% n 0.4wt 5 ,- 0. 0.0 d 7an ively. It is difficult to achieve these accuracy for carbon and ash in brown coal containing chlorine using the commercial nuclear gauges.

2.4.2 Technique

In order to overcome the above problems for low rank coals, CSER.O has developed a gauge (Figure 1) which uses a high energy neutron source (such as 24IAm-Be or ^Pu-Be) to strongly excite the 4.43 MeV inelastic scatter gamma-ray from carbon. Previous work has shown that this techniqu usee b measuro dt n eca e carbo blacn ni k coa withio t l 4 n0. well[6]s % gauge A .wt th , e use higsa h efficiency bismuth germanate (BGO) detectoo rt improve spectral quality and reduce background compared to the NaI(Tl) detectors used in the commercial gauges.

In the pulse-height spectra of prompt gamma-rays obtained from the BGO detector when a brown coal sampl s irradiateei d with fast neutrons followine th , g features s showa , n ni Figure 2, are predominant and well separated in energy: the 511 keV peak due to

Shaker tube

Coal sample

22mm thick steel cord conveyor belt (on-belt Samplx eBo geometry)

OD 76 x 76 mm 370 GBq BGO detector 238Pu-Be neutron source

Tungsten shield

Figure 1. Schematic diagram of the nuclear gauge used for the laboratory analysis of Victorian brown coal samples.

20 1000 o O O 800- X

00 c 600- D O

o 400- CL\_> J2> 200- E D C

0 60 0 40 0 20 channel number

Figur . e2 Typical pulse height spectrum fro gauge mth Figurn ei showine1 positione gth s selectef o d spectral regions.

annihilation gamma-rays, the 2.22 MeV peak due to neutron capture by hydrogen, the 4.43 neutroo t pea V e kdu Me n inelastic scatterinregioV Me n carbon8 y gb 6- peake d th an , n si due to neutron capture in chlorine (6.11, 6.62, 7.41, 7.79 MeV) and to neutron inelastic scatterin oxygey gb n (6.13 MeV) strengte annihilatioe Th .th f ho n pea gooa ks i d indicator of the ash content based on the pair production method [7]. The annihilation peak is due primaril e interactioth e strono yt th f go n 4.4sourcV 3Me e gamma-ray wit e coahth l sample.

determinatioe Th sodiue th f nmo conten browf o t n coa importans i l t sinc sodium/ase eth h ratio is an indicator of the boiler fouling propensity of the coal. There is a strong correlation between sodium and chlorine in many Victorian brown coals (Figure 3). Since prompe th t gamma-rays from sodiuweao to direcr e kfo m ar t determinatio f sodiuno mn i brown coal determinatioe th , f sodiuno m conten bess i t t don measuriny eb chlorine gth e content. When iron is used in gauge construction the 7.64 MeV peak from iron dominates the 7.41 and 7.79 MeV peaks from chlorine, whilst the 6.62 MeV chlorine peak is obscure escape th y db e peaks fro iroe mth n peak, thus makin combinee gth d chlorind ean bese th oxyge t indicatoV Me n 1 peachlorinf 6. ro t ka e content (and hence sodium content) samplee inth .

geometro Thertw e ear y option nucleaa r sfo r on-lingauge th r eefo analysi browf so n coal on a conveyor belt or in a shaker tube. These are a backscatter geometry in which the sourc same th detectod e sampln ean transmissioa o th sid e d f eo ar re an n geometrn yi which the source and detector are on opposite sides of the sample. In the case of an

21 0.5

0.4 JD T3

0.3

O C/5

O

rms erro 0.03r= % 7wt correlation coeff = 0.957

4 0. 3 0. 2 0 0.1 0.5 Tabulated Sodium (%d.b.)

Figur . e3 Correlatio f sodiuno m predicted from laboratory chlorine analysis with sodium determine chemicay db l analysisample 0 Yany 11 Lo r gf sfo so brow n coal.

on-belt measurement transmissioe th , n geometr advantage th s yha beinf eo g less affected disadvantagee th s ha bele bt yth bu t lowef so r coun beintf o rate d g san strongl y affectey db variations in coal thickness. For coal samples of thickness greater than about 200mm, the backscatter gauge is not affected by coal thickness. In addition, the backscatter geometry is better suitemeasuremene th do t carbof o t n inelastic scatter gamma-rays thesr .Fo e reasons, a backscatter geometry is preferred for both on-belt and shaker tube measurements.

The sensitivity of the gauge to changes in hydrogen, carbon, ash and chlorine were measured using coal sample whicn si h these elements were artificially increasee th y db additio , respectivelynof , water, coke, sancommod dan n salt. Counting statistical errors were calculated from the measured net photopeak count rates and total window count rates estimatee Th . d counting time determino st e carbo withio nt wt%4 n0. , hydrogeo nt within 0.07 wt% and chlorine to within 0.01 wt% are respectively 550, 6 and 1500 seconds.The chlorine counting time can be reduced to about 200s if a background windo requiredt no ws i .

2.4.3 Method

experimentao Tw l geometries were used firse Th t. geometry, simulatin gconveyoa r belt polyethylenm m 0 41 x econfiguration m boxm 5 , int49 ox whicm ,m consiste5 h 54 a f do the sample was packed to a depth of about 300 mm, resting on a piece of 22 mm thick steel-cord conveyor belt (Figure 1). For the second geometry, simulating a shaker tube configuration, the sample was packed to a height of about 800 mm into a sealed polyethylene, cylindrical tube of 350 mm outer diameter.

22 Measurements were carried out on 36 Latrobe Valley coal samples (sets 1 and 2 in Table 1) in a simulated on-belt geometry, and on 12 samples (set 2 in Table) in a shaker tube geometry. A ^Pu-Be neutron source and BGO detector in backscatter geometry were used (Figure 1) with a counting time of 20 minutes (excluding dead time) The gross numbe f counto r s withi 0.511e nth peakV , 2.22Me s wer1 , 6. 4.4 ed extracte3an d from each gamma-ray spectrum additionn I . numbere th , countf so s within selected background regions (Figure 2) were recorded for each of these peaks.

chemicalle Th y measured value ashr sfo , carbon, hydrogen, sodium, moistur chlorind ean e content, as well as gross wet specific energy (GWSE) and the sodium-to-ash ratio, were correlated with the numbers of counts in appropriate regions of the spectrum using equation forme th f s:o

(1)

where Y is the quantity of interest, a0,a\ai^... are coefficients determined by multiple linear regression Xi,xd an ,e number 2th ...... e f ar countselectee o s th n i s d spectral regions.

In orde reduco rt effecte eth samplf o s e inhomogeneit laboratore th n yo y results, multiple measurements were mad somn eo e sampleresulte th d ssan averaged shakee th r rFo tub. e geometry this was achieved by averaging measurements taken for four rotations of the tube. For the on-belt geometry, seven spectra were collected from each of the 12 samples after remixing and replacing in the sample boxes or after vibrating to increase the bulk density.

66

65 CO

CD 64

63 CD O) =3 CO

CO _o> Ü 6! rms error = 0.93 wt% correlation coeff = 0.84

60 6 6 5 6 4 6 3 6 2 6 1 6 60 Chemical Laboratory Moisture (%a.r.)

Figur . e4 Compariso nucleaf no r gauge moisture with chemical laboratory moistur2 1 r efo Loy Yang brown coal samples in a simulated shaker tube geometry.

23 2.4.4 Results

resulte Th averagef so d multiple Yanmeasurementy Lo g 2 brow1 e th n n coaso l samplen si shaker tub on-beld ean t geometrie listee sar Tabl showd n di an Figuree2 n i s . 4,5,7 d 6an The r.m.s. errors obtained in both geometries are about 0.9 wt% for moisture, 0.2 wt% for ashMJ/k3 0. , GWSEr gfo 0.0d sodium/asr an ,3 fo h ratioimportans i t I . noto t e thae th t results presented here were achieved after reducin effecte gth samplf so e inhomogeneitys a , discussed above. The averaging of multiple laboratory measurements gives similar conditons to those which would be found in an industrial application, where the continuous movemen samplee th f o t , either alon gconveyoa r bel r througo t hshakea r tube, would minimis effecty ean s resulting from localised inhomogeneities.

The effect of counting statistics can be demonstrated by reference to the carbon measurements. Carbo determines ni d wit totaha botn i e l hth erro% f abouwt o r 6 0. t shaker tubon-beld ean t geometrie countine s (TablTh . ge2) time require determino dt e calculatee b n carboca d% withio nfrot wt correlatioe m4 th n 0. n equation aboue b o st 2 t nun and 12 min for the shaker tube and on-belt geometries respectively. The main reason for thi thicm s m kdifferenc 2 conveyo2 e th s ei on-belre belth n i t t geometry.

For the full suite of 36 samples in the on-belt geometry, the r.m.s. errors, as shown in Table 3, are 1.3 wt% for ash (0.4 wt% omitting a sample in which ash content was an order of magnitude higher than for the other samples), 1.0 wt% for moisture using a correlation with carbo correlatioa n r alon fo 0.8 d % ean 5 nwt including ash, hydroged nan carbon botr ,fo h0.0 % sodiu2wt chlorined man MJ/k3 0. , r GWSgfo e 0.0d th E an r 3 fo sodium/ash ratio. It should be noted that no corrections have been made to these results

1.4

1.2

CO

to

^ 0-8 O> 13 CO CD 0.6 CO CD 0.4

% tmwt s 2 erro02 r= 0.2 correlation coeff = 0.85

0 0.2 0.4 0.6 0.8 1 1.2 1.4 Chemical Laboratory Ash (%a.r.)

Figur . e5 Compariso nucleaf no r gaug with eas h chemica Yany lLo glaborator2 1 r fo h yas brown coal samples in a simulated on-belt geometry.

24 11

O) ^10.5

UJ CO o 10 o> cn 3 CO 9.5 tö -S? o rms erro 0.2r= 6 MJ/Kg correlation coeff = 0.90

0 1 10. 5 9. 5 9 11 Chemical Laboratory GWSE (MJ/Kg)

Figure 6. Comparison of nuclear gauge gross wet specific energy (GWSE) with chemical laboratory GWSE for 12 Loy Yang brown coal samples in a simulated on-belt geometry.

02. -

erros rm r «= 0.01% 9wt correlation coef 0.9= - f 7

0.05 0.1 0.15 02. Chemical Laboratory Sodium (%a.r.)

Figure 7. Comparison of nuclear gauge sodium content with chemical laboratory sodium Yany Lo conten g2 brow1 r fo t n coal sample simulatea n si d on-belt geometry.

25 TABLE 2. Summary of results obtained by correlating chemical laboratory assay with nuclear count rate measurements in both shaker tube and on-belt geometries for 12 Latrobe Valley samples (set 2 in Table 1). For explanation of symbols, see Figure 2.

Parameter Correlated with Shaker Tube On-Belt Correlation RMS error Correlation RMS error Coefficient (wt%)* Coefficient (wt%)* Ash 511,511b 0.90 0.18 0.85 0.22 Moisture Cp.Cbu 0.84 0.93 0.87 0.85 511,511b,Hp,Cp,Cbu 0.87 1.04 0.95 0.63 Carbon Cp,Cbu 0.89 0.68 0.88 0.62 GWSE Cp,Cbu 0.86 0.3 0.9 0.26 Chlorine ClOp,ClObu 0.89 0.02 0.94 0.02 Sodium ClOp,ClObu 0.93 0.03 0.97 0.02 *except GWSE (MJ/kg)

TABLE 3. Summary of results obtained by correlating chemical laboratory assay with a single measuremen f nucleao t r count rate eacn so h sampl on-beln a n ei t geometr6 3 r yfo Latrobe Valley samples (sets 1 and 2 in Table 2). For explanation of symbols, see Figure 2.

Parameter Correlated with Correlation RMS error Coefficient (wt%y Ash 511,511b 0.422 0.38 Moisture Cp,Cbu 0.88 1.01 511,511b,Hp,Hbu,Cp,Cbu 0.93 0.85 GWSE' Cp,Cbu 0.85 0.31 Chlorine ClOp, ClObu 0.87 0.02 Sodium ClOp,CIObu 0.94 0.02

1 except GWSE (MJ/kg) 2 excluding one very high ash content sample (23 wt%d.b.) sample2 1 3 s only (GWS includet E no assa b la remaininr yn dfo i g samples)

e effectfoth r f samplo s e inhomogeneity e extenTh . o whict t h laboratory results were affected by inhomogeneity was investigated for the subset of 12 samples used for the shaker tube tests. A significant improvement was observed particularly for correlations directly relate measuremento dt carboe th f so n peak, i.e. carbon, moistur GWSEd ean s a , show Tabln i . e4

26 TABL . E4 Summar f correlationo y e on-belth n i s t geometr Latrob2 1 n o y e Valley samples , (seTabl2 t , illustratine1) effece g th sampl f o t e inhomogeneity.

Parameter Correlated with Single measurement Average of seven measurements Correlation Rms error Correlation Rms error coefficient (wt%) coefficient (wt%)* Ash 0.511, 0.5b I 1 0.7 0.3 0.85 0.22 Moisture Cp, Cbu 0.7 1.24 0.87 0.85

511,511b,Hp>Cp,Cbu 0.78 1.32 0.95 0.63 GWSE Cp.Cbu 0.65 0.44 0.9 0.26

Excep* t GWSE (MJ/kg)

2.5 Microwave Technique

2.5.1 Background

Moisture measuremen microwavy b t e technique sdifference relieth dielectrie n sth o n i e c properties of water and the remaining coal matrix. Measurements of microwave attenuation for the determination of moisture in coal was reported as early as the 1960's. However, early commercial gauges based on microwave attenuation have not found widespread acceptance in the coal industry due to the significant effect of coal feed characteristics (e.g. particle size, ash content) on measurement accuracy. CSIRO have previously developed a microwave transmission gauge, based on a measurement of microwave attenuatio phasd nan e e on-conveyofrequenca shif th t r a GHz4 t fo 2- , f yo r determinatio f moisturo n blacn i e k coa e CSIRl Th [8]O. phase shift measurement technique allows moistur e determineb o t e t highea d r accuracy s thapreviouslwa n y possible with technology based on attenuation measurement alone. A prototype gauge was field tested at Howick coal washery in 1989 and the technique was licensed to MCI Ltd in July 1990.

In the present investigation, CSIRO has developed a microwave gauge specifically for the on-line determination of moisture in Victorian brown coals. The special requirements of this application are very high measurement accuracy (approximately 0.8% relative error compared to 5% relative error that is typically acceptable in a black coal application) and the ability to analyse at high microwave attenuations approximately 60dB for 30 cm brown moisture)% wt 5 coa6 t .la

2.5.2 On-Belt Measurement Geometry

The laboratory prototype microwave gauge for on-belt moisture measurement is shown schematicall Figur n ythii n I s . geometrye8 microwave th , e transmitte received ran r horns e mountear d verticall positioned yan d approximatel aparte gamma-ram m Th .0 45 y y transmission gaug alss ei o mounted vertically directly behin hornse dth linn i , e wite hth aparthorncoae m m Th l s.0 samplecentrem 56 m d 5 an ,, containe49 (54x x 5bo a n di cross-section and 410 mm height) at a depth of 300 mm is positioned immediately above the transmitter horn or gamma-ray gauge for measurement.

27 Figure 8. Schematic of prototype microwave transmission gauge for measurement of moisture in brown coal directly on a conveyor belt.

Measurements on coal samples were performed at a frequency of 2-3 GHz. The phase shift and attenuatio e transmitteth f o nd reflectean d d signals were determined usina g microwave network analyser (Hewlett Packard 8719A) mase r uniTh .spe e t th are f ao sample, determined by the gamma-ray transmission gauge, was used to correct for variations in the sample density. Laboratory measurements were made on the coal sample at five positions within the box. This was necessary to minimise errors arising from inhomogeneities in sample packing in the experimental setup. The measurements from the five positions were then averaged to give the final sample analysis.

The microwave data was correlated with moisture using equations of the form

Gauge Moistur , (6/wa (A/w^ + s 0 a )+ e)= (2)

Gauge Moisture = a0 + a, 6 + ^ (A) +a3 (w) (3)

where a0 , a, , a^ , ... are fitting constants, 9 and A are the microwave phase shift and attenuation respectively, and w is the sample mass per unit area. The correlations on the dat aVictoria5 3 obtaine e Tabln i th ) coa2 r n e1 d fo d (set l an sample 1 son-bele th n si t measurement geometry are given in Table 5. For the 35 Latrobe Valley coal samples, the moisture was determined with an r.m.s. error of 1.06 and 0.97 wt% using Equations (2) an) respectively(3 d . These r.m.s. errors include error contributions from samplind gan variability of sample packing as well as the analysis technique.

28 TABL . ESummar5 f o ycorrelation microwavn o s e moisture gauge dat r Latrobfo a e Valley brown coal samples in the on-belt measurement geometry.

Data Set Number of Moisture Equation Correlation RMS RMS data points Range Coefficient error error (wt%) (wt%) (%reL) Latrobe 35* 59.3-68.5 2 0.87 1.06 1.7 Valley (Vie) 35* 59.3-68.5 3 0.9 0.97 1.5

*One sample (with high sulphur content) of Set 1 in Table 1 omitted.

2.5.3 Shaker-Tube Geometry

laboratore Th y prototype microwave moisture gaug shakee th n ei r tube geometr shows yi n schematically in Figure 9. In this geometry, the microwave transmitter and receiver horns e mountear d horizontall positione d gamma-rae apartbeae m th yan m f Th m o .7 d38 y transmission gaug s alignee samwa th e en i d e horn' planth s sa e centr d mountean e d horizontally opee closcoag k th nl0 o e t 5 sampleshorns e Th . , containe shakea n di r tube x 100 height)m D 0O m s place m wa , m (35d0 vertically betwee e openth n hornd an s gamma-ray gauge for measurement.

The measurement techniqu shakee th r erfo tube geometr similas ywa thao rt t describen di section 2.5.2. However thin i , s geometry, measurements were coa e madth l n sampleo t ea

Microwave Printer Computer Network Analyser (Hewlett Packard ) 9A 1 87 r Disk Drive

Figur . e9 Schemati f prototypo c e microwave transmission gaug r measuremenfo e f o t moisture in brown coal in a shaker tube.

29 t eigha d tht ean position tubm m e 0 heighs40 arounf o t tube dth e circumference. This procedur s necessarwa e o minimist y e errors arising from inhomogeneitie n sampli s e packing in the experimental setup. The measurements from the eight positions were then average givo d t finae eth l sample analysis. These measured microwave parameters were correlated with moisture using Equations (2) and (3).

TABL . ESummar6 f yo correlation microwavn o s e moistur Yany Lo e g 2 gaug1 r efo brown coal samples in both shaker tube and on-belt geometries.

Data Moisture Equation Shaker Tube On -Belt Set Range (wt%) Correlation RMS error Correlation RMS Coefficient (wt%) Coefficient error (wt%) Loy Yang 60.8-65.5 2 0.96 0.47 0.93 0.65

3 0.94 0.43 0.95 0.59

correlatione Th date th an obtaineso d fro twelve m th Yan y eLo g coal sample shakee th n si r tube geometry are given in Table 6 and Figure 10. For the purpose of comparison, the correlation results for the same group of samples in the on-belt geometry are also given in Table 6. In the shaker tube geometry moisture was determined with an r.m.s. error of 0.47

66

65

UtrJ 64 ID I— CO O 63

Q UJ 62 O Q rUrJ 61 rms error = 0.43 wt% correlation coeff = 0.97

60 4 6 3 6 2 6 1 6 0 6 65 66 MOISTURE (wt%)

Figure 10. Plot of microwave predicted moisture versus laboratory moisture for measurement Yany Lo g2 1 sample n so s shakea (Se Tabln n i i t) 2 r1 e tube geometry . (Fig9) .

30 and 0.43 wt%, using Equations (2) and (3) respectively. In comparison, for the coal samples measured in the on-belt geometry, the equivalent r.m.s. errors were 0.65 and 0.59 wt% moisture respectively. An improved accuracy was obtained for the samples in the shaker tube geometry because it offered better control of the microwave transmission path compared to an on-belt geometry. In addition, the coal depth and profile on the conveyor belt may vary significantly, whereas these are effectively constant in the shaker tube geometry.

2.6 Commercial Gauge The present investigation on nuclear and microwave techniques for the on-line analysis of low rank coal involves sha detaileda d compariso on-belf no t (wit hfixea d coal thicknesf so 300 mm) and shaker tube measurement geometries with regard to measurement accuracy. The r.m.s. errors for the nuclear technique are not significantly different for the two geometries l caseal n i s d excepan , t moisture e accuracieth , s achieve adequate dar r efo most applications. However, it is important to note that these results were achieved after removing the effects of sample inhomogeneity, which tends to increase the r.m.s. errors for carbon and any quantities derived from measurements of carbon peaks, such as GWSE and moisture e determinatioTh . f moisturno microwave th y eb e techniqu s significantlewa y better in the shaker tube geometry which was attributed to improved control of the microwave transmission patlesd hsan variatio e samplth n ni e dept profild han e using this arrangement r practicaFo . l application f bot o se nuclea hth microwavd an r e gaugen i s on-belt geometries, variations in coal thickness and profile will introduce additional errors.

In addition to improved measurement accuracy, the advantages of the shaker tube geometry include: shorter analysis time; better radiation safety; abilit analyso yt e more than one stream; insensitivity to vertical segregation of coal; and less engineering development. Consequently, on the basis of the above advantages and industry interest in the installation of an on-line analysis system at the earliest possible date, CSERO proceeded with the commercial development of a gauge using the shaker tube measurement geometry.

The nuclear and microwave techniques for on-line analysis of low rank coal were licensed to Mineral Control Instrumentation (MCI) Ltd in September 1992. The shaker tube geometr yCoalscae useth n di n 9000 analyser on-line th r ,fo e manufacture d Lt I MC y db analysis of black coal, has been adopted for the present application. This has involved optimisatio type dimensiond th ean f no f shieldinso g materials (fo ^Am-Be rth e source) an e designe nucleadth th microwavd f o san r e gauges e firsTh t . commercial gauge, marketed as the Coalscan 9100, was installed in late 1993 at Loy Yang B Mine of the State Electricity Commission of Victoria to measure ash, moisture, specific energy and sodium content n additioI . o providint n g real-time coal analysis informatio r operationafo n l purposes, this system should provide a basis for the open cut to bill the power station when acceptable accurac proves yi fielde th .n ni

3 PULVERISED COAL MASS FLOW

3.1 Background combustioe Inth f pulveriseno d coa r steafo l m generation ther e certaiear n controllable energy losses caused by operating under non-ideal conditions. These losses are due to

31 incomplete combustion of both solids and combustible gases and losses due to the need for excess air. Als non-unifore oth m distributio pulverisef no d coal between burner feed pipes lead localiseo st d area f incompleto s e combustion, slaggin foulingd gan , increaseX dNO emissions and a reduction in boiler efficiency. In practice, the controllable losses due to incomplete combustion and excess air show a minimum as a function of oxygen in the flue gas. These losses can be reduced by balancing the burners and then adjusting the excess ai operato rt e nea minimume rth .

In pulverised coal-fired boilers, coal is pulverised in mills and then transported pneumaticall heatea yvi d primar r througyai h feed pipe burnero st s withi boilere nth A . typical large coal-fired boiler will operate with about seven pulverise burnersr0 4 mill d san . The mills pulverise the feed coal to a particle size of about 75% through a 75 micron screen. The coal-air mixture is blown out of each mill into about six burner feed pipes of

diameter 300 to 600 mm at velocities of about 25 m/sec. The coal and air densities in these pipe respectivele sar mg/cm2 1. yd . abou3 an Non-unifor 8 0. t m distributio f pulveriseno d coal between the burner feed pipes leads to localised areas of incomplete combustion, increased slagging and fouling, increased NO emissions and a reduction in boiler

efficiency. Ther cleaa s ei r reliablneea r daccuratfo d ean e on-line instrumen measuro t X e the mass flow rates of pulverised coal in feed pipes into large coal-fired boilers. The measurement technique should preferably be non-invasive, accurate to within about 5% relativ inexpensived ean instrumentt presenw A .fe e th t s which have been developed have not found widespread acceptance or use in the power generation industry.

A number of on-line pulverised coal mass flow instruments, based on ultrasonic, microwave and beta transmission techniques, have previously been developed to prototype stage and installed in industrial plants. However none of these instruments have found wide e poweth us n i er generation industry. British Coal Utilisation Research Association (BCURA) developed and field tested a pulverised coal mass flow meter comprising an ultrasonic gas velocity meter combined with a beta-particle absorption meter for coal densit yearle [9]th yn I .1980's , Moun Minea Is t s Ltd, Australia, develope gaugde a th r efo determination of coal mass flow in the feed to a copper reverberatory furnace based on beta transmission and electric charge fluctuations in the dust [10]. In practice, the major disadvantag above th f eo technique hazare th s f si usindo g radioactive beta-ray sources separated from an abrasive and hostile atmosphere by only thin windows. More recently, Wayne State Universit Availabld an y e Energy Inc. [11] have develope ultrasonin da c techniqu whicn ei h solids loadin measures gi d fro meae mth n attenuatio transmittee th f no d ultrasonic beam flod an w, velocit determines yi d fro dowe mth n strea mbeae th drif mf o t whic measures hi physically db y movin ultrasonie gth c transmitte r receiverro . Microwave techniques have been investigated for coal mass flow measurement by at least two groups. Kozlak [12] developed a microwave fuel flow detector which relied on the measurement of the attenuation of a microwave beam across each of the feed pipes from a mill. Howard [13] also used microwave attenuation for measuring coal loading but incorporated a Doppler measurement to determine the particle velocity.

The CSIRO Divisio f Minerano Procesd an l s Engineerin e developingar g ultrasonid can microwave techniques for on-line measurement of pulverised coal mass flow, and have evaluated these techniques on a pilot scale recirculating dust rig.

32 3.2 Closed Loop Recirculating Dust Rig

In order to evaluate ultrasonic, microwave and beta-transmission techniques under realistic conditions larga , e closed-loo recirculatinr p fo dus g ri t gvelocite dusth n i t 0 y4 rango t 0 e1 s m/beeha s n designed, installe d successfullan d y r laboratorytesteou g ri t a de Th . comprises about 20 m of 310 mm internal diameter steel pipe including two 1.5 m long straight test sections. The rig includes a 840 mm diameter centrifugal fan driven by a 18.5 kW moto controlled ran variabla y db e frequency speed controllerg ri .int d Duse ofe th s i t via a 3 litre capacity dust feed hopper installed on the low pressure side of the fan. Dust clean up is achieved using a cyclone of height 5.3 m and diameter 1.0 m into which the dusty air can be directed by a series of valves. o dateT , dust measurement e recirculatinth n i s g havri g e been made with glass microspheres, sand, alumina ashpowdey fl . d Glasran s microspheres havee proveth e b o dt best materia t breathed readil e theno s significantl an p a lyar k o u yg d ri y e availablth n yi e commercially in a number of size fractions. Coal dust has not been used as equipment has not been installe controo dt whic g oxygee ri th l e h th wiln n requiree i conten b lr ai f o do t avoid the possibility of explosion. Ultrasoni3 3. c Method The ultrasonic mass flow gauge being develope CSIRy b d O comprise o pairtw f s o s broad-beam transducers positione oppositn do e pipe sideth ef so carryin pulverisee gth d coal to the boiler. The first pair of transducers are used to determine the transit times (tI2 and t21 ultrasonif )o c pulse botn si h direction floe th w t abouo st a direction ° 45 t . Velocity (V) is then determined from the equation:

2sinocoso

pipe wher floth e anglee s th i wdiamete th e o d e t directiona d ran principlen I . , bote hth transit tim attenuatiod ean n measurement made b n e sca wit same hth e pai transducersf ro . However, we have found difficulty in obtaining reliable amplitude measurements with the 45° transducer havd san e therefore use seconda d pai f flush-mounteo r d transducero st determine the attenuation of ultrasound transmitted perpendicular to the flow direction. Flush mountin s usei g o minimist d e window erosio r duso n t build-up which affect attenuation measurements. Ultrasonic attenuatio s affecteni boty b r turbulencd hai d ean dust loadin correctioa d effece gan th f turbulenc o r t nfo s requireei determino dt e dust loading. Pulverised coal mass flothen derivewe nca b d fro measuremente mth velocitf so y and mass loading. In view of the low cost of the transducers, additional pairs of transducers can be used to obtain average flow rates around the pipe.

Most tests on the rig to date have used commercial 215 KHz lead zirconate titanate (PZT) discs with soft rubber front faces. A CSIRO developed electronics and software package pulse transducere dth amplifiedd san , digitise analysed dan receivee dth d signals. 3.3.1 Velocity

The accuracy of the ultrasonic velocity technique has been assessed on the recirculating comparisoy b dus g ri t n with pitot tube measurement r flowai r . sfo Standar r velocitdai y

33 35-

correlaîion coeff =.999 rms erro 0.35m/r= s V) E J o 20-

|l5- 10-

0 3 5 2 0 2 5 1 10 35 Pitot Tube Velocity (m/s)

Figure 11. Comparison of average air velocity determined using a pitot tube with that determined from 45° ultrasonic transit time measurements.

measurements were made using pitot tubes at 20 positions across the horizontal and vertical diameters of the duct, according to British Standard BS1042 Part 2A, 1973. A compariso pitoe th f tn o tub e measurement ultrasoni° s 45 wit e hth c technique showed that the ultrasonic technique could be used to measure air velocity to within about 0.35 m/s over the range 10 to 30 m/s (Figure 11).

r dustFo y flows, ultrasonic velocity measurements were compared wite velocitth h y determined by a cross correlation technique using two beta-ray gauges mounted 72 cm downstream c 0 8 apar d tan m fro ultrasonie mth c gauge. Glass microspheres (D50 valu7 e6 microns) were added to the rig over a range of dust loadings from 0.18 to 0.65 mg/cm3. A compariso e crosth f so n correlation measurement ° ultrasonis45 wite th h c technique showed that the ultrasonic technique could be used to measure velocity in dusty flow to within 0.48 m/s over the range 23.5 to 32 m/s.

3.3.2 Mass loading

The measuremen f duso t t loading using ultrasonic attenuatio s calibratenwa d usinga beta-ray transmission gauge located 75 mm from the 90° flush-mounted ultrasonic transmission gauge. The beta-ray gauge comprised a 370 MBq (10 mCi) krypton-85 diametem sourcem 5 2 ra , plasti thiccm scintillatoja k 0 aluminiu10 d an r m windows flush e pipebeta-ramountee th e sid Th f .th o e n ydo gauge directly measures mass loading independent of turbulence.

Tests were performe closed-looe th n do p «circulatin t fiva eg gri differen t settinge th f so variable frequency speed controller e controlleTh . s initiallwa r t sucse yr hai thae th t

34 velocity in the rig was 32.5 m/s before addition of a fixed quantity of dust (glass microspheres with a D50 value of 67 microns) to the rig. The controller was then varied s downwardincrementm/ 5 2. o 22.n t si s 5 m/s. Ultrasoni d beta-raan c y data were compared for 88 sec intervals, during which 20,000 ultrasonic wave forms were collected. e accurac e ultrasoniTh th f o y c gaug s estimatewa e compariny b d e dusth g t density determined by the beta-gauge against the ultrasonic measurements with corrections for turbulenc temperatured ean . Combining data from measurements ove range th r e 22.5- 32.5 m/s the error was 0.041mg/cm3 (7.4% relative). This error reduced to 0.021 mg/cm3 relative% (4 fixet )a d initia (Figurs velocitr m/ lai 0 e3 f 12)yo .

o examinT e effec eth f particlo t e densite th siz n f duseo yo t ° determine90 e th y db ultrasonic transmission gauge a second dust (glass microspheres with D50 value of 116 microns testes recirculatine th ) wa dn i g chang e rigTh . particln ei e size e fro firsth e mo th t t second dust caused a bias of 0.3 mg/cm3 over the entire range in the density determination. The change in particle size used here is about a factor of four greater than the maximum change encountere a boile n i d r fee o dmilt e linl weardu e n practiceI . , o errort e du s changes in particle size could be corrected for by infrequent recalibration of the ultrasonic gauge over the lifetime of the mill.

Microwav4 3. e Method

The microwave mass flow technique involves a combination of a microwave transmission measurement to determine dust loading and an independent measurement of dust velocity by either an ultrasonic velocity measurement (section 3.3.1), a microwave Doppler reflection measurement [14 crosr ]o s correlatio microwavo tw f no e gauges.

0.9 0.8- correlation coeff =.987 CO rms error = 4.0%rel 1 0.7- o 0.6- 0.5- VI 0.4- o

0.2- 0.1- CH 9 0. 8 0. 7 0. 6 0. 5 0. 4 0. 3 0. 2 0. 1 0. 0 0.

Beta Transmission Density (mg/cm3) A

Figure 12. Comparison of dust density determined by beta-ray transmission with that determined by ultrasonic attenuation at a velocity of 30 m/s.

35 MICROWAVE RECEIVER BETA TEFLON DETECTOR WINDOW

DUST FLOW

U BETA vi SOURCE MICROWAVE TRANSMITTER

MICROWAVE NETWORK ANALYSER

Figure 13. Schematic of microwave transmission gauge for on-line measurement of pulverised coal mass loading.

To determine the loading, a 10 GHz microwave signal is transmitted across the pipe throug fluso htw h mounte thicm m k d2 PTF E windows e signaTh . s transmittei l d dan received by two pyramidal horn antennas (Figure 13). A measurement of the complex transmission coefficien systee th f mrecordeo s ti microwava y db e network analysere Th . transmission coefficient may be expressed as:

i £ 81 (5)

where A is the measured attenuation in dB and 9 is the measured phase in degrees. The transmission coefficient can also be expressed as a function of the dielectric constant (e') anlose dth s tangen ) [14] measure(5 e t .Th d phas attenuatiod ean thue nar s relatee th o dt dielectric constant and loss tangent of the material analysed.

The dielectric constant and loss tangent of the coal air mixture within the pipe is dependent temperature th d mixturee an ratie th or nf th f coaai eoo o o t l. Therefore, measurine gth phase shift across the pipe and the air temperature within the pipe, the ratio of coal to air withi mixture determinede nb th y ema .

In order to evaluate the microwave mass loading technique, microwave measurements were compared with measurement masf so s loading fro mcalibratea d beta-ray transmission gauge describes a , section di n 3.3.2. This beta gaug locates ewa d approximatelm m 5 y22 upstream of the microwave horn antennas.

36 Tests were made by introducing a known quantity of dust into a fixed velocity air stream. Microwav betd eaan gauge measurements were recorded oveminut0 3 ra e period, during which the change in air temperature was typically approximately 10°C. Both the microwav betd eaan dataverages awa d ove totae rth l time period changiny .B amoune gth t materiaf o l introduced int streae oth loadine mth varies gwa d ove range rth e 0.0 50.4o t 5 mg/cm3. Tests were performe m/s)5 3 e t d eacvelocitie3 d.a Th an f ho s m/s5 m/ s(2 0 ,3 results indicate that, for data at a single velocity, the loading could be determined to within 0.025 mg/cm3 (11% relative shows )a Figurn i . Change e14 measuremene th o st t system between runs at different velocities made it difficult to combine the data. Consequently, for correlations on the combined data the r.m.s. error increased significantly to approximately relative% 20 t . expecte problea Thi no practicae e s b i sth mn o di t l applicatioe th f no technique involvin gfixea d installatio gaugea f no .

3.5 Industrial Prototype Gauge

A field trial is planned at a New South Wales power station during 1994 to assess both ultrasoni microwavd can e techniques under industrial conditions o recomment d an , e dth optimum gauge for further development and commercialisation. The field trial will involve the installation of ultrasonic and microwave sensors on one output pipe of a mill. Four pairs of ultrasonic transducers, one pair of microwave sensors and two beta-transmission gauges will be installed on the test pipeline. The beta gauges are for calibration purposes fixea t dno componene ar onl industriad e yth an f o t l prototype gauge on-line Th . e mass flo f pulverisewo d coal determine gaugee th y db s wil comparee b l thao dt t obtained from conventional sampling methods, and analysis by a beta-transmission gauge.

0.4

CO

& CO £0.+ 2 Q 0) lo.i + o rms error = 0.025mg/cm3

0 0 0.1 0.2 0.3 0.4 Beta Density (mg/cm3)

Figure 14. Plot of microwave predicted mass loading versus mass loading determined by the beta-transmission gauge, at a flow velocity of 25 m/s.

37 4. CARBON IN FLY ASH

4.1 Background e on-linTh e measuremen f unburao t woulh t as carboe ideally db fl n ni y carriey b t dou determining the average value across the large (-4x4 m) flue ducts in a power station. Howeve methoo rn doinf do beet gye nthis thredevisee sha th ed previousldan y developed instruments [5,15] all continuously extract small quantities of fly ash from the ducts. Two thesf o e instruments determine carbo combustiony nb measuriny b producee CO on , e gth d

anothee d th measurin y b r g mass lossthire Th .d instrument measure2 s carbo infrarey nb d reflection threl Al . e instruments have significant disadvantages.

CSIRe Th O Divisio f Minerano Procesd an l s Engineerin bees gha n investigating nuclear [15] and microwave [15,16] techniques for the rapid and accurate analysis of fly ash samples, which in an industrial instrument would be extracted from the duct via a cyclone, filter or similar device. The nuclear technique best suited for carbon determinations is neutron inelastic scatterin g e 4.4 carboV baseth 3Me n o dn gamm y [6,15]ra ae Th . technique has the advantages of measuring carbon directly and of being insensitive to moisture, but the disadvantage in the present application of being unsuited to bulk samples f maso s less becausthag k highle n3 th f eyo penetrating radiation used. Laboratory tests on 123 fly ash samples from six Australian power stations showed that neutron inelastic scattering could be used to determine carbon content of 5 I samples (each weighing about 3 kg) to within 0.20 to 0.29 wt% for fly ash from individual power stations [15]. The main sourc f gaugo e e erro thesn i r e measurement s countinwa s g statistics, which coule db reduced by increasing either the counting time or source strength, or by measuring larger samples.

4.2 Microwave Technique

Measurement of wt% unburnt carbon in fly ash using microwave techniques is based on the high real or imaginary part of the complex dielectric constant of unburnt carbon compared wit dielectrie hth c propertie e remaininth f o s g matrix (principally oxidef o s silicon, aluminiu iron)relative d man Th . e complex dielectric constana s i e'- = " £ jte

functio dielectrie th f no c constant (e')an lose dth s facto ash/aiy fl r e (e"rth mixturf )o d ean r is therefore affected by both the carbon concentration and bulk density of the fly ash. In practice it is the influence of these changes in dielectric properties on more easily measured parameters suc microwavs ha e phase attenuatioshifd an t n tha determineds ti . three Th e measurement geometries evaluated involved measurement sampleh as y fl n si n so a simulated on-conveyor belt geometry, a microwave waveguide and a PTFE tube at the axis of a cylindrical microwave resonant cavity (MRC). The conveyor belt and waveguide geometries were suite measuremento dt bul, n whereaC so kg k MR sample w e fe s th a f so technique required samples of ~3g. Laboratory measurements on 123 fly ash samples from six Australian power stations indicated thae microwavth t e technique could determine unburnt carbo withio nt r.m.sn na . erro 0.08-0.2f individuar o fo % 8wt l power stations. predictee Th frodh carboas m y fl microwav n i e measurement samplen so s from Bayswater power station is shown in Figure 15.

38 o CD OC

ü u UJ 0 U UJ DC Q_ UJ 0.5

O cc rms error = 0.08 wt% 0

o 0.5 1 1.5 LABORATORY CARBON (wt%)

Figure. 15. Plot of microwave predicted carbon versus chemical laboratory carbon for Bayswater fly ash samples.

4.2.1 Industrial Prototype

The neutron inelastic scattering technique has the advantage of measuring elemental carbon directly. However, compared with the neutron inelastic scattering technique, microwave techniques have the advantages of rapid analysis time, higher accuracy at low carbon content, adaptability to small sample size and no requirement for bulky radiation shielding. Consequently, the microwave technique was selected as the most suitable technique for field three trialsth f e O microwav. e techniques developed microwave th , e resonant cavity (MRC) techniqu e advantageth s ha e f simplicityo s , small sample sizd equivalenan e t accurac othee th ro yt microwav e techniques smale Th . l samplC make) eg MR siz 3 e es(~ th technique suitable for use with commercial automatic dust samplers.

The industrial prototype MRC gauge is shown schematically in Figure 16. The fly ash collecte CEGRIa y db T automatic dust sample droppes ri d directle porp th y f to int o t e oth gauge and fed, with the assistance of vibratory feeder, into a PTFE tube that carries the vibratory feeder that carries it through the microwave resonant cavity. A valve located beneath the resonant cavity is kept closed to allow fly ash to accumulate in this tube. The filling of the tube is continuously monitored, and when sufficiently filled a microwave measurement is initiated. The filling time is governed by the sample feed rate from the CEGRI approximatels i d Tan minutes3 y2- microwave Th . e analysi completes si 2 1- n di seconds. After completing the analysis of the sample it can be either collected (via a plug valve sampla n )i e container locate dblowe beneatb n n ca gaug e bact hi th r keo inte oth duct using a short blast of compressed air.

39 \ CEGRIT / \ Sample/ r l-ri-i-T-H-i

Vibrator

PTFE Vibrator tubing Level Sensor

Flyash Microwave ""' Sample Resonant Cavity

Plugc Valve X - Compresser dAi

J Sample Collection Bottle

Figur . Schematie16 desigf co f industriano l prototyp gaugC on-linr eMR efo e determination of carbon in fly ash

microwave Th e analysis involves measurin change gth resonann ei t frequenc resonand yan t power of the microwave cavity containing fly ash compared to that for an empty cavity. The resonant frequency and resonant power of the cavity both decrease with increasing wt% carbon in the fly ash as shown in Figure 17. Consequently, determining the difference in resonant frequency and peak power, between fly ash filled and empty cavities, compensates for any errors in measurement due to temperature drift.

There are two main practical problems to be overcome in the application of the microwave techniqu routine th o et e on-line determinatio powea n i h r as stationf carbo no y fl n ni . Thes firstle ear ensuro yt controlleea d flo throug h flf wyo as gaugee h th secondlyd an , o t , ensure that the sample analysed is representative of the fly ash being expelled from the boiler.

microwave Th e techniqu bees eha n field tested using CEGRIT Automatic Dust Samplers (Mark II) to supply fly ash to the gauge. The field test commenced in April, 1991 at Wallerawang power station, NSW. Two gauges were installed on separate ducts from the No. 8 boiler at the station. One of these gauges analysed fly ash collected simultaneously by three CEGRITS at different vertical positions in the duct. Simultaneous sampling from these three CEGRITS allowe assessmenn da samplinf o t g bias. Durin tria e unburne gth lth t carbon from the three CEGRITS typically agreed to within 0.5 wt%, indicating that there was a relatively small sampling bias between the three sampling points.

40 An off-line calibration of the gauge was obtained by filling the sample tube of the gauge with fly ash of known unburnt carbon content and measuring the change in resonant frequency and peak power. Correlations with unburnt carbon indicated that carbon was determined wit r.m.sn ha . erro(Figur % 0.3f o rwt 9 e 18), ove range rth eusin % 4-1wt g4 change th pean ei k power on-line Th . e calibration involved collectio sampla f no e ovea r minut5 2- ecorrelatioe perioth d laboratore dan th f no y determined carbosample th f no e wit gauge hth e analysis. Approximatel sample0 y80 s were collected during July-August data 1991r a Fo averagin. g perio f abou do houre r.m.se on t th , . erro unburnn i r t carbon carbon% wt s 6 1.0.ove1 % rangwa e Thio 3th wt t r se7 error include erron a s r from chemical laboratory (loss on ignition) analysis of 0.25 wt%. It was found that a large componen measuremene th f o t variatioo t h e bule tas du th erro ky s n fl i densit rwa e th f yo filling the sample tube. The principal cause of this was the unexpected large variation in sample collection rate fro ducte mth . Whe nmeasuremena bulf o t k density ancillarn a y b , y beta-ray transmission device s incorporatewa , correlatioe th n di n with carbo e r.m.snth . erro approximatels rwa y halved alternativn A . e metho densitf do y compensation, basen do onl microwave yth e data alss oha , been developed.

4.2.2 Commercial Gauge

Mineral Control Instrumentatio d havnLt e been license manufacturo dt marked ean e th t MRC gauge for the on-line measurement of carbon in fly ash. The design of the commercial prototype gauge is similar to that in shown Figure 16. However, on the basis f experienco e gained durin fiele g th dCSIR e th tria f o Ol industrial prototype gauge eth sample collection mechanism has been redesigned. Intermittent blockage of the plug valve

600

480 Empty Cavity

360 - Flyash CD Filled o240 -\ Cavity Q.

120 -

0 1.85 1.87 1.89 1.91 1.93 1.95 Frequency (GHz)

Figure 17. Plot of transmitted power versus frequency for the microwave resonant cavity gaugeC peake MR Th .e isnth corresponfilleh as d y emptn fl PTFa d o dt yan E sample tube.

41 in Figur cause6 e1 d problemsampleh as collectioe y fl th . e n sConsequentli th f no y3-waa y plug valve was relocated above the measurement cavity, and sample collection performed b ythough directinas y hfl thie gth s valv intd eoan collectioa n bottle r purgeusinai n ga . The commercial gauge is able to be mounted on a standard fly ash cyclone sampler (such a CEGRI s a T Automatic Dust Sampler) analysid ,an performes si minut5 3- t da e intervals. Also gauge th , bete doeus a t transmissiosno measurinr nfo g sample density t insteabu , d incorporates a density correction factor derived from the microwave data. The first commercial gauge was installed at Bayswater power station, NSW, in March 1993.

5. CONCLUSION

Nuclea microwavd ran e techniques have been develope on-line th r defo determinatiof no moisture, ash, specific energ foulind an y gran w indelo k f coalo x . Mineral Control Instrumentatio havd nLt e been license manufactureo dt marked an t on-line gauges based on these techniques and the first commercial gauge was installed at a Victorian power station in late 1993.

Ultrasonic and microwave techniques have been developed, and evaluated on a recirculating dust rig, for the on-line measurement of pulverised coal mass flow. Industrial prototype gauge presentle sar y under development plannes i t i d fielo dt an , d trial thesa n ei New South Wales power station during 1994.

Microwave and nuclear techniques have been investigated for the on-line measurement of unburnt carbon in fly ash, and an industrial prototype gauge, based on a microwave resonant cavity analysis technique, has been trialed at a New South Wales power station.

16 cT- $ o 14 oCQr < o 12 Q UJ oI- 10 o UccJ Û- 8 UJ (D

1« rms erro 0.3r= % 9wt Orr

6 8 10 12 14 16 LABORATORY CARBON (wt%)

Figure 18. Plot of the off-line calibration of the industrial prototype MRC gauge in Fig. 16.

42 Mineral Control Instrumentatio havd nLt e been license manufacturo dt marked an e e th t gauge, and the first commercial unit was installed in March 1993.

ACKNOWLEDGEMENTS authore Th s wis thano On-Linhe t stafth e kf th o f e Analysi Electronicd san s Groupe th f so CSIRO Divisio Mineraf no Procesd an l s Engineerin their gfo r contributio projectse th o nt . The authors gratefully acknowledg e assistancth e f stafo e f froe Statmth e Electricity Commissio Victorif no Pacifid aan c Powe projectse th n worri e partls Th .k wa y supported by grants fro e Nationamth l Energy Research Developmen Demonstratiod an t n Council and Pacific Power. Additional financial support was received from Mineral Control Instrumentatio durind nLt developmene gth Coalscae th f o t n 9100 gauge.

REFERENCES

] Sowerby[1 , B.D., Nuclear technique coae th l n sindustryi , IAEA Symposiu Nuclean mo r Techniques in the Exploration and Exploitation of Energy and Mineral Resources, Vienna, Austria June8 5- , , 1990 3-32. pp , .

[2] Cutmore, N.G., Howarth,W.J., Sowerby, B.D. and Watt, J.S., On-line analysis for the mineral industry, Proc. AusIMM Centenary Conference, Adelaide, 30 March- 4 April 1993, 189-197.

[3] Cutmore, N.G., Lim, C.S.,Ottrey, A.L., Sowerby, B.D. and Yip, V., On-line analysis ranw lo k f coalo , Proc. Internat. Symp On-Linn o . e Analysi Coalf so , Vienna, 10-13 October 1993.

[4] Sowerby, B.D., Millen, M.J., Abernethy, D.A. and Wagner, S. "On-line determination f pulveriseo d coal mass flow usin ultrasonin ga c technique", 1991 IEEE Ultrasonics Symposium, Lake Buena Vista, Florida, 8-11 December 1991.

[5] Cutmore, N.G., Abernethy, D.A., Evans, T.G., Millen, M.J., Sowerby,B.D. and Yip, , On-linV. e analysi coal-firen i s d power stations, InternatProcA EE . . Sympn o . On-Line Analysi Coalf so , Vienna, 10-13 October 1993.

] Sowerby[6 , B.D., "Measuremen f Specifio t c Moisturd Energyan h Buln eAs i , k Coal Samples by a Combined Neutron and Gamma Ray Method", Nucl. Instr. Mem. 160 (1979), 173.

] Sowerby[7 , B.D. "Determinatio ashf no , moistur specifid ean c energ f coal"yo . IAEA Advisory Group Meetin gamman o g , X-ra d neutroan y n technique e coath ln i s industry, Vienna. 4-7 Dec. 1984, (1985), 131.

] Cutmore[8 , McEwanEvansd N. ,an . T , . "On-conveyor determinatio f moisutrno n i e coal", J. Microwave Power and Electromagnetic Energy, 26(4), 1991, 237.

43 [9] Pickering, A.R., Pope, C.W. and James, K. "Performance of BCURA pulverized fuel mass flow mete t Aberthaa r ' Powew'B r Station", CEGB Report SSD/SW/H.533 (March 1973. )

[10] Cunningham, J.B., Fox, M.J., Henley, R.G. and Whitworth, N.R. "Development of a coal mass flow monitor". Aus. I.M.M. North Queensland Branch, Smelting and Refining Operators Symposium 1985y Ma , .

[11] Leffert, C.B. and Weisman, L.H. "Ultrasonic measurement of velocity and/or solids loading", International Patent Publicatio 87/0569O W . Sept4 nNo 6 (2 . 1987).

[12] Kozlak, M.J. "Microwave Detectio f Fueno l Flow", United States0 Patent83 8 62 , Dec. 1986.

[13] Howard, A.V. "A microwave technique for monitoring the mass flow rate of pneumatically transported solids", 3rd International Conf. on the Pneumatic Transport of Solids in Pipes. Proc., (Bath, England), April 1976, 53.

[14] Evans, T.G., Cutmore, N.G., Zoud, E. and Paoloni, F.J. "Microwave techniques for on-line determination of pulverised coal mass flow", Proc. 1992 Asia Pacific Microwave Conference, Adelaide, 11-13 August 1992, 559.

[15] Abernethy, D.A., Cutmore, N.G., Doumit, S.I. Evans, T.G., Millen, M.J. and Sowerby, B.D. "Developmen techniquef o t on-line th r sfo e determinatio unburnf no t carbon in fly ash", Proc. IAEA Symp. on Nuclear Techniques in the Exploration and Exploitation of Energy and Mineral Resources (IAEA, Vienna, 1991), IAEA-SM-308/2, 1991. 71 ,

[16] Evans, T.G., Yip, V., Cutmore, N.G. and McEwan, A.J. "Microwave technique for on-line determination of unburnt carbon in fly ash", Proc. 1992 Asia Pacific Microwave Conference, 11-13 August 1992, 563.

44 NUCLEAR BOREHOLE LOGGING TECHNIQUES FOR COAL QUALITY

M. BORSARU CSIRO Division of Exploration and Mining, Glen Waverley, Victoria, Australia

Abstract

The progress achieved by nuclear logging in the coal industry has been significant. The 'in- situ' information about coal seams provide boreholy db e loggin significantln gca y reduce exploration and development costs. Nuclear borehole logging is used routinely in the exploration for coal and is getting more acceptanc minine th n ei g stag qualitr efo y control. Nuclear borehole loggin uses gi o dt delineate the coal strata and to determine their thickness, depth, ash content, calorific value and Fe and Si content of ash.

techniqueo Tw s have been develope lase yearth 7 t n coar di sfo l loggin boreholesn gi :

(i) The spectrometric gamma-gamma for the determination of ash content in coal and prompe Th (iit ) neutron-gamma methodeterminatioe th r dfo f ashno , calorifie F c d valuean i S , in coal.

In this paper both gamma-gamm d neutron-gamman a a techniques were developer fo d delineatin coae gth l seam predictind san contenh as e coalneutron-gamme n gi th t Th . a techniqus ei superior because it can also determine the Si and Fe content of coal and it can sample a larger volume of coal. The neutron-gamma technique is less affected by the rugosity and condition of the borehole.

1. Introduction progrese Th s achieve nucleay db r loggin coae th l n gi industr bees yha n significantn 'i e Th . situ1 information about coal seams provide boreholy db e loggin significantln gca y reduce exploration and development costs. Nuclear borehole logging is used routinely in the exploratio gettins i coar d nfo an lg more acceptanc minine th n ei g stag qualitr efo y control. Nuclear borehole loggin uses gi delineato dt coae eth l determino stratt d aan e their thickness, depth contenth as , , calorifi conteni S d ashf an c o t e valuF . d ean Nuclear logging and the analysis of the core retrieved from the cored holes are not exclusive but complementary analysie core .Th th e f provideso maximue sth f informatiomo n which can be extracted from the hole. Nuclear logging provides less information. However, due to the deep penetration of the neutrons and gamma-rays, the volume of coal sampled by nuclear logging is much larger than the core samples, thus providing better sampling statistics. Nuclear logging also provides results almost instantaneously. The full information given by the analysis of the core is not always required and the information provided by nuclear logginquite b n e gca adequate reaa n lI . mining operation both core oped dan n holee sar drilled and all the holes are logged. Two techniques have been developed in the last 7 years for coal logging in boreholes: (i) The spectrometric gamma-gamma for the determination of ash content in coal and prompe (ii)Th t neutron-gamma metho determinatioe th r dfo f ashno , calorific d valuean i S , Fe in coal.

45 2. The Spectrometric Gamma-Gamma Technique For Coal Ash Determination in Boreholes e gamma-gammTh a technique used routinel coae th ln yi minin g industr developes ywa d durin gresolutiod 1970sbe e Th . n (BRD), high resolution (HRD long-spaced )an d (LSD) density logs are. use delineato dt coae eth lconten h seams as estimate e e b coaf n o tTh . ca l d fro correlatioe mth n which might exist betwee contenh nas densityd an t spectrometrie Th . c gamma-gamma technique develope lats measuree contenth eh 80 n das i e coan th si t l from correlatioe th n betwee Zeqd an , giveh whers i n as q y nb e Ze

ZM=3.5 (1)

e weighth e ar t fractioi Z atomid d wheran an n i p ec numbe particulaa f o r r elemental constituent, i, in the scattering medium and Ai is the atomic mass of the element. For an unique relationship between ash content and Zeq, ash content can be determined by measuring changes in Zeq. The most common method to measure the change in Zeq is the measurement of Pz, which is the ratio between count rates recorded in two broad spectral window energiesw lo higt s a d determinatioe han .Th contenh as f no t fro measuremene mth t of the Pz ratio is accurate only if Zeq and ash content are uniquely correlated. This only occurs whe chemicae nth l compositiostables i h e mosas .Th e t th dominan f no t elementn i s hige s it th valuehZ o s t i contene variatioe F e h th ,e as Du th n . i t f no Fe d an i S , Al e ar h as most important factor which affect accurace th s coa f determinationyh o las .

Figur showe1 s three backscattered gamma-ray spectra measure coadn i l sample differenf so t ash content usin ga 133B a gamma-ra e ratiy th source os i betweez P . coune th n t rates measured in the spectral windows b and a and is related to Zeq. Figure 2 shows a cross-plot betwee predictioh as e nth n fromeasuremenz P ma chemicas v t l assay (Borsar t al.ue , 1985). The rrns deviation of ash given by the regression equation was 2.1% ash. The standard deviatio sample th f no e populatio s 5.6nwa % ashe gamma-gamm.Th a technique th r efo determination of ash in boreholes can be used in both dry and waterfilled boreholes. The logging tools can be sidewall or centrally operated. The centralised tools use larger detectors and require primary sources of moderate strength e.g. 37MBq 137Cs. Spectrometric logging tools using microsources were also developed recently toole Th s. employ gamma-ray sources of activity less than 1.8 MBq. Due to the very low gamma-ray source activity and light weight, these tools are ideal for use with portable logging systems or logging horizontal holes in underground mining operations.

. Promp3 t Neutron-Gamma Loggin Boreholen i Coar h gFo As l s The prompt neutron-gamma technique for the determination of ash, Si, Fe and calorific value of coal was developed in the late 80s - early 90s (Charbucinski et al., 1986; Borsaru et

46 6xIC -

40 SO \20 IOC ENERGY

Figure 1. Typical backscattered gamma y spectr—ra coaf o a l samples with a Ba gamma-ray source. The shaded areas indicate near-linear regions of the spectra: (1) 7.1 %ash; (2) 21.5 %ash; and (3) 36.8 %ash.

al., 1988; Borsaru et al., 1991; Borsaru et al., 1993). Due to its high hydrogen content, coal bese th t f applicatiomedie o th e r i son neutron-gammae fo th f no a technique neutrone .Th s get thermalised by colliding with the hydrogen nuclei and interact with the nuclei present in the coal. The gamma-rays produced by the neutron capture process have energies above 3 MeV (see Table 1). By contrast, the gamma-rays produced by neutron activation, neutron inelastic scattering, or natural radioactivity have energies mainly below 3 MeV; this makes the prompt neutron-gamma technique less sensitive to interferences from other neutron

47 responsa - ; r - e« 25 » Rs = 0.234 G2.1= " h %cs 20 -

!5 -

10 -

5 2 0 2 5 1 10 % Ash (chemical analysis)

Figure 2. Comparison of coal ash content determined by chemical analysi measuremend an s . Pz f o t

interactions. Also deeple th , y penetrating neutron higd san h energy neutron capture gamma- radiation, sampl elargea r volum f coaeo l than doe gamma-gamme sth a metho thid dan s make e neutron-gammth s a technique less sensitiv e rugositth o conditiot ed yan e th f no borehole radiation.

contenh as coaa e f to lTh sampl weighe th s ei t percentag residuf eo e after combustios i d nan therefore relateminerae th o dt l conten f coal determinatioo e t Th . contenh as f ncoao n i t l correlatioe relieth n so n which exist maie sth betweend constituentan h i nas S i.e, h as .Al f so and Fe or a combination of two of these elements. Charbucinski et al. (1986), developed a method based on the neutron-gamma technique for the delineation of the coal strata and determination of their thickness and ash content in boreholes. The neutron-gamma logging too 252Clg consisteji detectoO 7 fsource0. a neutroBG a d f dm o ran m - n1 5 source x 1 5 a , to-detector spacing of 15 cm. Figure 3 shows a cross-plot of ash values determined by regression analysis of the neutron-capture data vs laboratory assays for ash content. The root-meen-square Th . diametemm boreholee 0 th 10 f ro s e swa (r.m.s. ) deviation between regression analysis predictio laboratord nan y contenassayh as r sfo t varied betweed an 4 n1.

48 Table 1. Neutron capture data for major components in ash

Gamma-ray Major intensity (I) Eiement Cross-section ;>ravs neutro0 10 r npe (atomic mass) c (barn)* (MeV) radiative captures

Aluminium 0.23 7.72 27.4 (26.98) 7.69 42 Suicon 0.16 7 "> 7.8 (2S.09) 638 11- 4.93 617 3.54 68.0 Iron 2.55 ".65 211 (55.85) '.63 2.O Titanium, ö.l 6.76 242 (47.90) 6.56 4.7 6.42 30.1 4.88 52 1.38 69 Calcium 0.43 6.42 38.9 (40.08) 4.42 14.9 1.94 715 Sulfur 0.52 5.42 59.1 (32.06) 4.87 11.5 3.22 27.1 193 223 238 44.5 0.84 75.5 inerma* l neutron capture.

8 wt%2. . This includes samplin laboratord gan y analysis errors. This techniquh as r efo determinatio boreholen ni s work botn i s h waterfille boreholesy dr d an d . However,e th calibratio predictioh as r nfo water-fillen ni boreholey dr d dan differente sar neutrone Th . - gamma techniqu determinatioe th r t affecte coaefo n no i s h i llarg y as db f neo variationf so coan i gamma-gamm s la e F . Neutron-gammais therefors ai e more suitabl logginr efo g coal deposits with high variatio contene F n i t (Borsar al.t ue , 1991). deee th po t penetratio e Du neutrone th f n o higd san h energy gamma rays resulting froe mth capture process the neutron-gamma technique is more suitable than gamma-gamma for logging larger diameter borehole gamma-gamme th f si a too centraliseds i l comparisoA . n between the gamma-gamma and neutron-gamma techniques for ash prediction in water filled quality control boreholes of 140 mm showed that the neutron-gamma technique was superio predictinn i r contenh coae as th e lf gth seamo t s (Borsar t all.ue , 1993) coae Th .l seams had high variation in Fe.

49 % ASH (StROLOG)

ro ui CO Ul o o en o en o en o T'- T~ nr~ nr

en

O" > IE -V. O IE m en

O CO \

tCOn

en

en o

Figur . 3 eCompariso contenh as f o nt determine y chemicab d l analysid an s predicted from the neutron-capture logging data.

4. Neutron-Gamma Logging for Fe in Coal e slagginTh g propert coaf s immediatyo ha l e consequences when burn furnacea n i t . Coal with slagging potential promote creatioe sth clinkef no r which prevents heat transfer whet ni accumulates around heat transfer pipes. At a coal mine in Australia work carried out by the mine geologists has shown that Fe is strongly correlated with the slagging index of coal. An empirical relationshi derives pwa regressioy db n analysi estimato st slaggine eth g indef xo coal from its ash iron content. Therefore, the slagging index of coal can be estimated by the determinatio concentratioe F f no ash n ndeterminatioi e . Th interrelatee ar h as f irod no dnan because in order to determine the percentage of iron in ash, the coal ash value must be known. The neutron-gamma technique was employed for the determination of both Fe and coan i lh (Borsaras t al.ue , 1993a exploration )i n borehole qualitd an diametef so m y m 0 10 r control holes of 140 mm diameter. Figure 4 shows a cross-plot of the chemical assays and

50 7 r Deposits Dünn Cree Trad an kp Gaily

345678 e (laborator%F y assays)

Figur . 4 eCompariso e contenF f o nf coa o t l predicte neutron-gammy b d d an a chemical assays. e neutron-gammth a prediction e conten coaF e th r l fo sn i seamt s give y regressiob n n analysis. The r.m.s. deviation between the neutron-capture predictions and laboratory assays was 0.88 % Fe. Figure 5 shows the iron content predictions at 10 cm intervals, for a section boreholee o th fcontene F dire e th t n bandTh .i t mucs si h highee %F rcoale e thath Th n .ni printe onls i d indicatio n ycontente a everm c F 0 e 1 e yverticath f Th . no l resolutioe th f no probe for ash and Fe prediction is about 50 cm. which means that the probe can predict ash and Fe content in coal seams not less than 50 cm thick.

11 10 9 S 7 6

4 D D P n« 3 2

l a n D on D a___i 13 14 15 16 17 IS Depth (m) Figure 5. A typical neutron-gamma log of a coal seam for Fe content.

51 u» N)

Table 2. Iron and ash concentrations in coal predicted by neutron-gamma logging and by laboratory assays

Laboratory Neutron-Gamma Difference Thick, %Ash %Fe in ni e %F %Ash %Fe in %Fe in %Ash %Fe in %Fe in Hole (cm) coal ash coal ash coal ash cl771 133 28.1 1.00 3.58 30.6 2.3 7.4 -2.5 -1.3 -3.8 57 18.7 0.60 3.16 19.4 1.2 6.2 -0.7 -0.6 -3.0 145 10.9 1.66 15.20 13.5 1.1 8.2 -2.6 0.6 7.0 190 33.0 3.60 11.00 31.0 4.2 13.6 2.0 -0.6 -2.6 271 19.6 1.20 6.10 19.0 1.6 8.3 0.6 -0.4 -2.2 190 23.4 0.65 2.78 20.7 2.4 11.5 2.7 -1.8 -8.7 490 14.1 3.26 23.10 15.8 2.6 16.1 -1.7 0.7 7.0 c2473 100 30.0 1.39 4.63 31.8 2.7 8.6 -1.8 -1.3 -4.0 147 24.3 5.00 20.90 23.7 5.9 24.9 0.6 -0.9 -4.0 320 21.6 5.10 23.50 23.9 4.9 20.4 -2.3 0.2 3.1 303 16.2 2.60 16.20 18.3 2.6 14.1 -2.1 0.0 2.1 c2467 296 17.0 3.20 18.70 18.9 3.9 20.5 -1.9 -0.7 -1.8 269 21.9 2.56 11.70 22.1 3.2 14.6 -0.2 -0.6 -2.9 178 17.0 0.90 5.35 15.3 1.3 8.5 1.7 -0.4 -3.2 (popD S ) SD 6.2 1.5 7.7 1.8 0.8 4.4 The neutron-gamma predictions for ash and Fe content in coal seams were tested against laboratory assay thren si e cored holes. Fourteen samples were availabl comparisonr efo e .Th samples were section corwere d th an e f eiro d so analysean n h laboratore as th e n di th r yfo content cor4 1 lengte e sectionth Th . f ho s chose comparisor nfo . n cm varie 0 49 d o frot 7 m5 Table 1 lists the ash and Fe laboratory assays and the neutron-gamma predictions for the 14 samples chose comparisonr nfo standare Th . d deviations betwee chemicae nth l assayd san neutron-gamma predictions were calculated usin formulae gth :

= 1M (2) l

where pred, and obsj are respectively the neutron-gamma prediction and laboratory assay for numbee th s i samplesf n samplro d standaran e , ei .Th d deviations were 1.8% ash, 0.8% iron in coal and 4.4% iron in ash. The standard deviations for the population were 6.2% ash, 1.5% iron in coal and 7.7% iron in ash respectively. A compariso alss nowa made betwee slaggine nth g index predicte neutron-gammy db d aan laboratory determinations on 15 samples collected from three cored holes. The results are give standare Tabln ni Th . e2 d deviation calculatee th d an d I usinS 5 5 g s formulwa ) a(2 standard deviatio populatioe th . r 81 nfo s nwa

. Conclusion4 s Both gamma-gamm neutron-gammd aan a techniques were develope delineatinr dfo e gth coal seam predictind san conten h as e coal gn th neutron-gammi te .Th a techniqu superios ei r because it can also determine the Si and Fe content of coal and it can sample a larger volume of coal. The neutron-gamma technique is less affected by the rugosity and condition of the borehole.

REFERENCES

Borsar , CharbucinskuM. Youd an F.(1985. , Eisle . S lJ. i L . rP ) Determinatio contenh as f no t in coal by borehole logging in dry boreholes using gamma-gamma methods. Geoexploratio 503-518, n23 . Borsaru M., Charbucinski J., Eisler P. and Ceravolo C. (1988) Coal ash determination in dry boreholes by the neutron capture technique. Nucl. Geophys 2, 201 - 206. Borsar , CharbucinskuM. Ceravold , EisleJ. ian . rP . (1991oC ) Neutron-gamma logginn gi coal seams of variable iron content. Nucl. Geophys 5, 117 - 122.

53 Borsaru M., Millitz P. and Ceravolo C. (1993) Comparison between the gamma-gamma and neutron-gamma techniques for ash prediction in 140 mm diameter quality control holes at Callide Mine. Nucl. Geophys 7, 125 - 132. BorsarNichold an , . BiggS u M. s. W.J.FsM . (1993a) Neutron-gamma loggin r irogfo n ni coaimplicationd an l estimatinr sfo fusioh as e ng th characteristic t Callidsa e Mine. Nucl. Geophys 7, 539 - 545. Charbucinski J., Youl S.F., Eisler P. L. and Borsaru M. (1986) Prompt neutron-gamma loggin water-fillen i coar h gfo las d boreholes. Geophysic , 111s51 0 -1118.

54 TYPICAL CASES OF APPLICATION OF THE ISOTOP MONITORH EAS CHINN SI A

Y. HONGCHANG Coal Preparation Research Institute, Tangshan Branch, CCMRI, Tangshan City, China

Abstract

Ovee recenth r t d STH-yearsan e ZTHYth Y ,2 FH isotop, h as e monitors developed by the Tangshan Branch, CCMRI have been successfully applied in coal washing coking and power sectors to meet to a certain extent the requirement on rapid determination of coal ash Currently 40 more such monitors are in use, bringing about remarked economic and social benefits The microcomputer — based on—line coal calorimeter operating based on the on—line ash monitor on—iine micro—wave moisture meter also passed the ministry—level technical appraisal in I'^l The BHZ —1 portable laboratory intelligent isotope rapid ash determination monitor which w e developebegab y no 19^ o t Ma s n 3ha n i d passed the scheme selection and principle experiment phases The prototype produced determines the coal ash by using Y —ray transmission method with i Am'1mc 0 4s radiatio'a n source. Repeated experiments mad5 sample n o e s of clea ng 5 washesample ji coa d f o f an l rflotatioo s n concentrate collected respectively from Majiagou coal mine and Linxi Coal Mine, Kailuan Alining Administration have met with considerable success As compared with the resul f laboratoro t y =0.249 J analysiss < error rm e e foun b ar e s 2 o th t ,dwt' t 0 334.= an2O dwt c"c respectively Like Amdeth e i programmable mineral analyzer e monitoth , r require e sampl e weigheth sb o t e d Currentl sample th y e - ~ ~g 2 >weigh 15 s i t

i l>l'i'— iine Application oï the Z Till inteliecruaj isotope AMI Monitor

As compared ^vith on-lin h determinatioas e ni —iin oi syste ee th m system possesses some noticeable inherent leamres It is iovr in cost oi system make—up, simpl n designi e , eas o operatt y d flexiblan e n siti e e installation withou e nee th o t remoult d e sitth de condition d procesan s s equipment Furthermore the monitor can operate on a time—division basis to cater to the different needs with one monitor.

55 w coara l e washeTh y Dizon b l) d g Coal Washery, Guizhou Produce. China comes from Lhizhi mind Dizonan e g mine with quite different geological conditions t I fluctuate. s widely therefor h contentas n i e , resultinn i g higher clean coal ash which is found to often exceed the specified limit and correspondingly lowe e cleath r n coal yield. e Becauslimitatioth f o n ei conditionn o t instals a by-linl h as e measuring system n off—lina , e system e ZTH th baseh moniton Yas o d s wa r y 199applie Ma r determinatiofo 3n i d f o clea h n as ncoa e mainlth l f o y produce y jigginb d g machinw coara ld periodicaf o an e h as le th chec f o k feed. n Aintervaa 5 minutest 1 f o l a 15—k, g sampl s collectewa e d froe mth jig's overflow weir, which after being drained for a period of 5 minutes was then — 2 minutsen h a measurint as r intee fo th omeasurinx bo g g processe Th . data obtained coul e transmitteb d dg operato ji remotel e d displayeth an ro t y d on display unit in digital form to serve as a basis for the operator to take appropriate control measures.

The calibration accuracy obtained with 19 clean coal samples is (7=0.4224 wtu Cr with a mean measurement error of d'=0.3369 wt%. Subsequently a total of 258 clean coal samples were analyzed under the identical conditions s campareA . d with laboratory analysis e deviatioth , f o n

the actually—measured value obtained with 233 samples was within 0.3^. while that of 15 samples ranged from 0.3?c to O.Sc.Cr e Becausremarkablth f o e e performanc e mensurinth f o e g system envisaged a ZTH, h monitoYas s usewa dr starting from Jul , 1991 y 3 instead of using burning method. Field use of the monitor had brought about noticeably improved qualit d highean y r qualified rat f producto e . - .• 'ihr ieeù to the Coking Plant. Anyang Steel Co.. Henan .frounce comes irom nearby coal nune^ and even small local ones. The qualify of the cokt- produce s i adverseld y o affectevariatiot e du f do propert n f coao y l feed. Therefor a ZTHe h monitoYas — s mounteI I e samplinwa rth n o d g decr fo k e cleath nf monitorin o coa h las shippee th g d inte plan th oy eac b t h truck. A 20—kg sample taken according to the specified procedure from each truck was sent into the measuring box for a 2—minute measurement process. Based on the actually—measured value, the trucks with qualified coal were

56 From clean coal system

cleao T n coal system

1. Sampler 2. Electro-vibrating feeder 3. Measuring box 4. Coal level controller 5. Discharge electro-vibrating feeder 6. Source chamber 7. Radiating source 8. Detector 9. Cable 10. FHY ash monitor 11. y,p —16 printer 12. 0~ 10 MA or 4~20 MA DC output

Fig1 . Schematic Diagra e Flowsheeth e By—linf mth o f h o t As e Measuring System

allowe e unloadeb o t d d while those with unqualified coal were returned back to the coal supply unit. o simplifT y tube operation, calibratio 9 amalgamate1 e s madth wa t n or e d samples collected froe cleath m n coals supplie y threb d e major coal mines. e calibratioTh n accurac d meaan y n measuring error wer =0.614G e 9 wtc-wc and d =0.4672 wtc"c respectively, sufficient to meet the requirement of the tiser. If the three calibration curves were respectively plotted, a still higher calibration accuracv could be obtained.

57 l. Belt conveyor 2. Coal leveller 3. Moisture probe 4. Ash probe 5. . CablMicro—wav6 e e moisture . meteIsotop7 T h rCR monito as . e8 r monito . TPS09 r 5 microcompute . KC8K' 0r printer

Fig. 2 Block Diagram Showing the Principle of On—line Coal Calorimeter

2. Application of the FÜÄ' Ash Monitor in Coal Preparation Plants and Power Stations

The FH\ ash monitor is an integral isotope instrument with digital display develope t earliea d e rTangsha th time y b s n Branch, CCMRI. which operates on back scattering principle with low—energy y —ray as emitter. A d sucod h 8 meter2 n currentotai f e o l ar s t use. The monitor is mainly used for determining the ash of clean coal products of individual separators, particularly for monitoring on by—line the clean coal of jig. It is mounted either on the feeding side of a clean coal screen, or outlet of a centrifuge or the discharge end of a scraper conveyor. e typicaTh l flo wh measurin as diagra e th f mgo proces s showi s n Figuri n . 1 e The FH\ instruments have been in successful operation over the past Min5 . eNo Washer e x yearth si t a s y Fengfeng Mining Administration. Hebei Province d Xiayukoan , u Mine Washery. Shaiixi Province. The instrument has also found applications in power stations for monitoring the ash of pulverized coal in feeding bins of iurnace for improved fuel property and higher efficiency of power generating sets. Up to date five

58 more such instruments are in use in power stations at Jiaozuo, Henan Province t Yangzhoua d an , , Jiangsu Province.

—Z l e on—lisTh . o e Automatic Rapid Calorimeter

Calorific Valu t onl no f n importancoao a eys i l t inde n analysii x f o s coal quality, but also an important criterion based on which to fix the price of power coa e n pasChinai e methoth l th t n I e conventiona. dth s usewa d l oxygen bomb method which suffers from the drawbacks of being complicated in process and time consuming. In order TO obtain the real—time calorific valu r fixinfo ee pric th gf powe o e re nee coalth n automatid catei d r an ,fo r c control of coal quality, an on—line automatic rapid calorimeter developed by the Tangshan Branch, CCMRJ was put into operation at Jinggezhuang Mine Washery. uLailuan Mining Administration. It passed the ministry—level technical appraisal in 1991. Its operating principle is shown in Figure 2. t I consist a coa f lo s leveller n isotopa , h monitoras e a micro—wav, e moisture meter and a data processing unit. The data processing unit is compose f TPS0o d 5 micro—computer, K.C8 T monitor0 CR printee d Th .an r d moisturan h as e probe e fittear s d sid a frony sidd rea b en i an ert manner on the coal leveller above the belt conveyor. For ensuring the truthfulness of e measureth d value n effectiva , h datas ea h sensoas s i mountee r th y b d probe, enabling the- preceding effectiv ee maintaineb dat o t a d whenevee th r dept f coao h l e streabelth t n mconveyoo . mm s beloi r 0 w12 The micro—computer is inputted with the following empirical expression appliee min th r calcalatin fo t ea d e cabrifigth c valu f coalo e :

Q »«. «30.204= - 7 0.341 - 0.107« . A 1 M, 6

where.

f coao i h as—receivei As — r a A d basis; M, — Total moisture

59 The values of Anr and M, are automatically measured by the ash and moisture meters respectively, and the calculated data is then displayed on the screeT CR n together with print—ou s historia t c data. When user monitorinfo d e calorifi th gmixem m w 0 cra d —5 valu f o e coa n belo l t conveyo f 28o a moistur— h r 45°d —12as 6 witan c n f a ht o teo a . Jinggezhuang Coal Mine e acctiracth , y actually obtaine s

4. Development of the BHZ — 1 Prototype Portable Laboratory—size Intelligent Isotope Ash Monitor

Despite the fact that in 1992 a total of 459 on—line isotope ash monitor was in use worldwide for rapid ash determination with considerable success, conventional chemical analysis, commonly calle e burninth d g method is still used at most of the coal mines, washeries coking plants, power stations and habours. The burning method is known to be time consuming (about one hour). Troubles experienced in the use of other instruments are that the on—line ash meter is incapable of monitoring the ash of coal product of an unit separator, while the by—line monitor requires sampîing from main coal stream and sample sending back system, and the off—line system requires a 30—kg mannually— collected sample and its accuracy is adversely affecte y particlb d e d sizmoisturan e e content. Therefore e th wor n o k developmen a portabl f o t e laboratory—size isotop h monitoas e r rapifo h r as d e monitodeterminatioth f o re y require1993us s starte Ma e wa n o n Th i d.n s special samplin d preparatioan g n processes d onl an 2 ,minutey e requirear s d to finish the check with about 100 grants, of sample collected from the back—up sampl r routinfo e e chemical analysi e microcomputer—baseTh s d measuring syste s mi eas n operatioi y d capablan n f performino e g storage, display and print—out of serial number oi samples measured, count rate, ash value, date and rime. The arrangement of the emitter and detection units is shown schematically in figure 3 r thifo s measuring ' —ra, system ye th transmissio, n metho s i used d with low—energ i Am'mc s ( emitter—raa 0 "1 y e y Th bea. s mcollimatedi .

60 1. 2THY-II intelligent isotope ash monitor 2. Probe 3. Support 4. . Radiatin5 Sampl p gcu e sourc. Shielde6 e d containe . . Bas8 7 er Protective hood

Fig 3 . Schematic Diagra e Portablth f mo e Laboratory—size Intelligen Monitoh As t r

i i L3.C Aad (7.) .43 -8,8817389 2 9.75 0.3511419 L2.C 3 18.6 -8.4179840 4 10.35 8.3935989 .11.02 -8.3249340. A: ,2978764 LU ,3342185 L0.ee

9,08

8,E 537 14B 531 942 OPTION; Ni<*100 U=Pasrellp ^PageDown B=Back-Rep E=En«l-Calil>

Fig. 4 Calibration Curve of Flotation Concentrate, Linxi Coal Mine, Kailuan Mining Administration

61 114, ftad ftjd d 13,88 1 6,14-8,2819768 2 7.720,8387144 ,, 3 7.9 8.3199422 "•\ '12,88 4 11.3-0.3572222 6 5 12,40.2899953 ^N^ . -11,8 - - 8- U'T^,223??h i "v^^ o- .249272? \ 18.08 ~~ 9.88 "N* 8.08 ^\ 7.88 \f. 6,88

« t * 5,88 1159 1161 1163 1155 . 1167 OPTION: U=Pa«relip D=PaseDown B=Back-Rep E=End-Calib

Fig. 5 Calibration Curve of Jig— washed Coal, Majiagou Coal Mine, Kailuan Mining Administration

The detector used is a self —developed Nal scintillation counter, and the ZTHY-J1 intelligent isotope ash monitor is temporarily used as the main unit. Like Amdeth e l programmable mineral analyzer e monitoth , r requiree th s sample weigheb o t e d wit a hbalance . Currentl e samplth y e g weighlo s i t — 0.2g which is intended to be increased to 20g, and 5 sample cups will be use r cyclifo d c measurement. Repeated experiments have been made wite monito th h5 flotatio n o r n concentrate samples collected from Linxi Coal Mine, Kailuan Mining Administration. The calibration curves obtained are shown in Fig. 4. As compared with laboratory analysis e rootth , — mean— square errod meaan r n measuring error are CT =0.3342 wt^o and d'=0.2928 wtc/o respectively. Similiar experiments have also been conducted wit 5 sampleh f jiggeo s d clean coal product collected from Majiagou Coal Mine, Kailuan Mining Administration h calibratioas e Th . n curve obtaineJ < s showi d e n Figi nTh . 5 . " valued 0.223d an e respectively0.249d % ar san wt % 7 wi 2 .

Conclusions

The paper presents a general overview of the application of the ZTHY, isotop h monitorf thesas o e e e Us .monitor n coai s l washeries. coking

62 plants and power stations for rapid ash determination has brought about remarkable economi d sociaan c l benefitsd sucod h 0 monitor4 . n curreni e ar s t operation. Success of the development of the on—line coal calorimeter is of considerable significance in this country for fixing the price of power coal. The preliminary experiments made on the BHZ laboratory intelligent isotope ash monitor have produced favourable result. However it needs to be iniprov«^ thrmigh further experiment e developmenth d an , t wor s expectei k d e finishe *b e ofirs di tn i dquarte f nexo r t year.

63 DESIG CONSTRUCTIOD NAN GAMMF NO A TRANSMISSION GAUGE FOR DETERMINATION CONTENH AS E COATH TN I F O L

A. ABEDINZADEH . RAHIMIH , . RAHIMIN , , . MOAFIANJ . AMINA , I Atomic Energy Organization of Iran, NRC, Tehran

A. BANISALAM Kerman Coal Corporation, Kerman

Islamic Republi Iraf co n

Abstract More theyearo mtw s research wor design ko duaa f lno energy y-ray transmission gauge is reviewed in this paper. e gaugTh e after construction wil e instal b la larg n i le coal industry named Kerman District Coal Mines (KDCM). KDCM consists of several coal mines, so that, coal transported on a conveyor belt may be a non-homogenious mixture from one or more mines. Therefore, prior o gaugt e e design, primary investigatio dons i no identif et d evaluatan y e relationshith e p betwee e masth ns absorption coefficien h percent as (jxd f o an t) e mixturth r coaefo le beltrunninth .n o g Resultf o s investigation shows that, coal mixture calibratiot n no curv n ca e be used accurately for ash estimation in coal of individual mines and, essentialy, gaue may works to determine the ash percent with some limitations in this particular region. Therefore, design of gauge was carried out in the laboratory and after setting up, primary experimental calibration curve for the differenc. s gaug. m s obtained. i er ee Th betwee. d n an gaug h as e chemical assay is 1.17 wt% ash, for ash in the range of 32-44 s programmei (wt%) t I .r futurfo d o complett e d improvan e e th e gaugable r on-linb efo o et h determinations eas .

1. INTRODUCTION The theory of dual energy gamma-ray transmission gauge capable f on-lino e measurin h contenas e coaf o gth s t i wel l l known and briefly could be written as follows;

65 1 = I e~**2px 2 o2 ^

ln (Io2/I2)=

px = 1/M2 * in (Io2/I2)

in (I/I) = in

ln (Iol/Il) / ln (Io2/I2)

where :

Mas= sH Absorption Coefficien coalf o t . \JL = Mass Absorption Coefficient for high energy radioactive ^ source. = Intensit Ienergw lo f yyo without absorber I = Intensity of low energy after passing the absorber I = Intensity of high energy without the absorber O^ I = Intensity of high energy after passing the absorber £1

241 137 In the existing project Am and Cs are used as a low d higan h gamm energiey ara Bot. s h radioisotope e placesar n i d the same lead containe radioactiva s ra e source. Ifa reasonabl, e relationship betwee e masth ns absorption coefficient and ash percent of coal for a certain coal mine could be found, then a curve can be drawn to be fed to the gauge's compute r calculatiofo r y mash percenan as s r f o fo nt absorption coefficient measured values . We were interested to fint sucou da hrelationship e Kermath r n fo ,Distric t Coal Mines (KDCM). Kerman District Coal Mines,are located about 100soutm K 0 h easf to

66 Tehran, and consists of several coal mines (Fig. 1). Coal from each mine is transported to the coal washing station(named Zarand) by trucks and then deposited in two seperate bunkers. So that,each bunker collect e ssam th coa ef o lquality . Then coal from each bunker is transported to the coal washing station by means of

KHOMRUDI

W ^HHOMRUDII

0 1 m 1 5K 5 0 . Km 5

DRAWMEH. Y H : RJÄ N BY Fi.g.1. General Kermanthe sketchof deposit.map 1-deposit contours; 2- outcrop of coal-bearing horizon ''D' - boundaries3 ;; f areaso d minean fields; 4- operative mines; mines5- under construction.

67 conveyor worts belti t hI . mentioning that, coal runnine th n o g belt is not necessarily mixture of all different mines, the most productive of which are Babnizo, Eskeli, Hojedk and Pabedana. Sometimes somo t ee technicadu , l difficulties, coar lo froe on m two mines might be fed to the belt. Even when there are coal from all differen te belt t doemineth t i necessaril no s,n o s y mean that the mixture is completly homogeneous . Investigation on the coal washing process shows that, addition of one percent of ash to the incoming coal, will results in two percent reduction in the efficiency of the product. Therfore it is very important to measure continuously the ash percent of the coal mixture just before entering the coal washing station . In order to avoid mixing of low and high quality coal, the best situation is to control the ash percent of coal just produced from each single mine before mixing with others n practiceI . , because of lake of conveyor belts and on line ash measure ing facilities, ash is only measured once a day, from mixture of several samples taken from coal running on the belt. e futur th o plar n installatios n therfo A i ene ar e f belo n t facilities for each individual mine, we decided to install the existin e gaugth n eo g belt, just before coal enterance th o et washing station . After installation place was cleared, we decideaheao g o dt dwit h proposee desigth f a no ds a gauge d an , first step we should find out the relationship between the n and ash percent of coal for KDCM. We collected samples of two hours periods from individual most productive mines mentione(a s d before) d alsan ,o from coal mixture runnin conveyoe th n go r belt. Samples were analyze theio t e r ddu moisture h percent,as , organic d inorganian d siliconan c compositio, N ,, O iron , H ,, nC suc ; has aluminium, calcium, magnesium, etc. From chemical analysis, theoretical mass absorption coefficient ( fi ) is calculated and relation between later parameter with ash percent of coal is drawn for each of the most productive mines and also for coal mixture runnin n gconveyoo r belt (see fig.2) y comparisoB . n between individual mines with coal mixture e camw ,e inte conclusioth o n

68 0.400

m n E 0.150

0.100 10 30 40 Ash(X) FIG. 2. Comparison between individual curves (1-4) with curve No. 5.

that mixture calibratio usee r b individua fo dt nno curvn ca le mines, or at least, there would be probably considerable errores which shoul measueree b d n long-teri d m trial. This probles i m discusse detail n r i firsdou n i st progress repor d alsn an i to 2 papee th r publishe y Nuclb d . Geophysr solutioOu .o thi t n s f o nucleoni e us h guagt r probleas eacge cfo e o hr KDCt fo ms Mi individua t possibleno thilf i s i smind ,an e feegauge'e th d s computer with different calibration curves, so that, each calibration curve may be selected into the operation by noticing which coa runnin s belte i l th .n go The theoretical research work during the first year of our project was important, leading us to get enough information about the compositio f coar differenno fo l t t coai lw KDCe No mine th . M f so is clear, what relationship exists betwee h percenas n d masan t s absorption coefficient for non-homogeneous coal mixture running conveyoe th w thin o ho rs d beltrelatioan , n coul e b usedr dfo » individual mines. e seconth n I r e dworkwer w ou yea ef , o r engage n i desigd f no the proposed gauge and performing necessary experimental work to

69 Mass Absorptio.n Coefficient Static Gauge Ash wt %

c3ppppppOC N N OJ en CDOOOOOOOC en . o en o O -———| ———— | ———— | ———— | ———— | ———— | ———— | ————

OJ - O • S= ft ct_ S- 04 o-. Cn g O) • 0 • j« Ä ^ fx n •fcl o / / W S te w o / / Q £$£- D C O O • 3 •tiis^ / / ~D 5~_ rt S' ta 3 / / à? rs S Ê o / / ° to' S 'o o ?0^ D _» • = 0> (sj ' o• ^8' rr i ^ (/) o> M 1 ^~ ô' i|| O if û •!. ü . '"e 3 - * o te s "— ' Cn" S' er. 1 è § Oi 00 ' l •0

en O 0.380 -r • Count rates corrected only du Refo et . sample 0.370-- CounO t rates, without correctio oeff( k Refo .d t e an . ndu c A Count rates, .corrected due to Ref. and k Coeff. v A Count rates, corrected only due to k Coefficient 'o k Coefficient = 0.06 Cs channel count rates

O ü C o

o w .u-

CO CO o

5 1 2 -1 9 ' 6 18 21 Coal thickness (cm.)

FIG. Variation5. resulta ofju as thicknessof (different curves obtaineda as result of different corrections applied countin rate measurements data).

0.400 Theoretical corr.:0.55 0,350 + Experimentav l

0.150--

0.100 0 10 20 30 40 50 60 70 (Chemical% t W h As )

FIG. Comparison6. between Theoretical Experimental& Calibration Curves.

71 BIT Signa o amplifiet l r Scintillation detector Detector lead collimator

Sodium iodid' e crystal

Y -ray

Glass Cylinder

Coal

Source shielding 137Cs Ç lead collimator

5 /o Cm SQVUi

FIG. 7. Schematic of the dual energy tf-ray transmission gauge on narrow beam transmission 24lof Kev)Am 4 137(60 Cs (660 Kev) %-rays.

12 understan gauge dth e working conditio accuracys it d nan . Therefore 7 13 1 24 poins C q GB t source4 d 7. an m f A so w e mad t orden ea ge o rt and 0.1 GBq respectively. We received our radioactive sources jusw weektfe s before writing thi meantimee sth n paperi e w d ,,an performed some experimenta e laboratorlth worn i k y scale using very low activity of the same radioisotopes. By such experimental worcoule w k d draw relative curve percen h betweeas d d tan an nn also variation of p. as a result of change in weight per unit area f coa o observes i l . d Thi sr s wor beeou ha park n f o t writte detailn r seconi n ou n i sd progress report submitte Agence th o yt d late December s 1993i d an , discusset no thin di s paper. Result sucf s o experimenta n ha l work were usefu r nex fo lte project th ste f po , whic settins i hf o p u g our industrial transmission gauge, schematic of which, is shown in Fig. .7

2. EXPERIMENTA RESULTd Lan S

calibratiod an p Gaug1 u 2. t ese n 2.1.1 p Gaugu t ese laboratore th n i d p consistan u y t Gaugse ; s of ei ) Measurina g head, scintillation detector 2.5x2.5 inchel Na s crystal collimated by lead . 241 v Radioactiv) Ke b 0 66 d an e ) sourcesAm ( , v consistKe 0 6 f o s (13 7 Cs) y-rays with 7.4 GBq and 0.1 GBq activity respectively, e mountesamth en i dcollimate d containe . Sourcer e placear s d opposit detectoe eth r wit. distancha cm 4 7 f eo ) Electronic c part, consist f pai o sf amplifiers o r , single channel analyzer counterd san s. Americium and Caesium intensities transmitted through the coal sample are analyzed by single channel analyzers, so that in the same time interval, count rate for Americium and Caesium is measured . Count rate measurements were in static position and coa s kep i n lglasi t s . diamete cylindee cm bea th 8 . m n f i ro r Computer with the 40 Mbyte capacity hard disc, will be added to thi neae s th par rn i t-futur . e

73 2.1.2 Count rate corrections Background count rates were measured ( with the sources shielded ) for Americium and Caesium, and each count rate measurement has bee nchannes correcteit o t l e backgrounddu . d All count rate measurement r Americiufo s d Caesiuan m e alsar m o corrected due to dead times which assumed to be the same for both radioisotope d equals an |ise 1 . s0 . c Another correction is applied for Americium count rates due to small fraction (k = 6%) of Caesium y-ray interference to the Americium channe. l This correction facto s i rdetermine d froe rati th mf Caesiu o o m count rate o\Ace Americiuth k m count rate whil a ethi n layef o r lead is applied on the sources beam . This layer of lead will absorb essentiall e Americiuth l al y m y-ray while ther s onli e y insignificant effect on Caesium y-ray . 2.1.3 Gauge calibration Twenty-three coal samples were taken from coal mixture on the conveyor belt, were used to get relation between ß and ash percent for KDCM. Samples were ground to powder size. Water wt% for KDCM coal is very low and therefore only samples were kept in room temperature before measurements. The y-ray transmission measurements were made with each of the 23 2 samples with abou 4 gr/ce 2 tbeaf th coao m. n m Eaci l h sample measures wa d thirty timesecond0 2 n i s s interval d measan n value of the count rates was taken as a measured value . Since we had not gain stabilize electronir ou n i r c par , t coal sampla s ea reference was measured prior to each sample measurement , and the mean value count rate measurements of the sample were corrected due to this reference variations . These data measurements were also corrected as mentioned in section 2.1.2 . Americium count rates as obtained above, was corrected again by empirical value a backgrounuse s a d r Americiufo d m channel count rates (see section 2.2 d )finaan l measuring data were useo t d calculate the ji values using equation (1) . Curve No. 3 shows relation between the \i values with ash% obtained by least squares

74 regression analysi Correlatio. s n coefficient calculate curvr fo d e 3 is 0.78 with 99% confidence level. Fig. 3 shows results of gauge ash in static position compared with chemical ash measured by standard method . The r. m.s.difference between gauge and chemical . assa h 1.1s as yi % 7wt Fig. No. 6 shows comparison made between the theoretical and experimental calibration curves. Experimental calibration curve is obtained using 23 coal samples, and may shift after addition of more measurements. 2.2 Errors weigho 2.2.t unir e 1pe tdu t Errorh are as coaf ao n si l Errors in determination of ash increases with decrease in weight per unit area of coal in the y-ray beam. Curve No. 1 in Fig. 4 shows variation of \JL values when weight per unit area of coal 2 - changes from 4.8 to 32 gr/cm , this variation of p. could be minimize applyiny b d g empirical correctio n Americiuni m measured data . Curve No. 2 in Fig. 4 shows result of such a correction applied. 2.2.2 Errors in count rate due to drift in electronic and gain Accurac f determinatioo y alsh as o f detectoe ndependo th n so r gain and electronic drifts, to minimize such an error, gain stabilizer will be used in our future work, and in the present worr measureou k d dats beeha a n correcte y checkinb d e th g reference sample prio samplo rt e measurement. s Different curve Fig.n i se obtained 5ar a resul s a f differen,o t t corrections appliee counth to t drates , including, correction reference th o t e e du sampl. e 2.2.3 Errores in ash caused by ash composition Table no. 1 shows a typical chemical analysis of coal samples for KDCM, and Table No. 2 shows variation of ash, water, and iron, calculated for few hundred coal samples . As it shows, iron variation in ash is rather high. Our measurments on two samples with the same ash content (chemical), but different Fe2O3 - ashn i ,% wt show significano sn tcalculaten changee th n i sy db equation (1). V.L. Gravi t is et. al and R. A. Fookes et. al ,

75 TABLE NO.I-RESULTS OF CHEMICAL ANALYSIS AND MASS ABSORPTION

COEFFICIENT VALUES FOR KDCM

s Ash conten h '/as . f to conten coalf to X cal.

NO. % A12o3 Fe2o3 Sio2 Cao Mgo K2o+ C H 0+N M Na2o

1 37.8 18.80 9.80 51.60 11.80 4.85 3.1 82.56 4.81 12.63 0.245 2 38.6 9. 10 18.60 62.20 4.41 3.75 1.9 82.67 4.36 12.97 0.261 3 32.2 18.10 19.15 52.10 6.80 2.90 0.9 84.92 4.41 10.67 0.251 4 24.0 27. 10 25.40 43.70 3. 12 1. 19 0.0 87.42 4.27 8.31 0.241 5 22.9 24.20 19.40 43.90 7.80 3.30 1.4 85.48 4.67 9.85 0.232 6 25.9 21.70 18.20 42.30 11.70 6. 10 0.0 79.50 4.73 15.77 0.239 7 25.1 22.80 21.70 45.60 6.90 1.60 1.4 84.32 5.07 10.61 0.241 8 26.7 13.86 28.44 46.90 5.27 1.86 3.7 83.46 4.65 11.89 0.258 9 26.7 16.80 23.30 45. 10 5.13 1.80 7.9 0.248 10 32.9 13.90 17.20 57.40 6.40 3.20 1.9 84.39 4.16 11.45 0.231 11 40.4 14.40 11.20 63.70 4.70 2.20 3.8 81.15 4.57 14.28 0.247 12 28.6 12.10 22.50 50.60 7. 15 1. 10 6.1 1 6 . 83 4.40 12.49 0.252 13 28.4 19.60 13.20 58.20 6.80 3.90 0.0 83.32 3.63 14.05 0.218 14 28.9 21.20 26.40 41.70 9. 10 3.40 0.0 81.86 4.69 13.45 0.259 15 37.8 27.70 17.20 44. 10 6.60 2.60 1.8 86.35 4,77 8.88 0.257 16 50.7 8.40 28.30 57. 10 3.78 1. 16 1.3 82. 14 4.99 12.87 0.315 17 55.5 12.17 26.40 49.20 7.70 3.25 1.3 84.33 5.42 10.25 0.328 18 54.5 10.30 23.60 58.60 6. 10 1.10 0.3 81.98 5.33 12.69 0.313 19 44.7 12.50 27.40 48.70 6.50 1.25 3.7 81.74 5.47 12.79 0.303 20 40.9 22.20 19.10 47. 10 8. 10 2.70 0.8 82.52 5. 10 12.38 0.271 21 45.4 19.90 16.80 55.20 7.70 3.20 0.0 82.01 4.79 13.20 0.272 22 45.5 26.60 13.30 51.70 6.10 2.70 0.0 81.75 5. 10 13. 15 0.260 23 45.9 25.60 12.10 53. 10 6.45 2.25 0.5 81.77 5.52 12.71 0.258 24 32.4 18.90 8.80 52.00 11.70 4.45 4.2 82.91 5.01 12.08 0.235 25 38.3 25.80 12.35 49.70 5.18 3. 12 3.8 80.60 5.21 14.19 0.247 26 32.3 23.30 7.96 63.40 7.70 2.27 0.0 86.88 5.04 8.08 0.229 27 52.5 17.80 22.80 46.30 8.80 4.30 0.0 85.07 5.45 9.48 0.308 28 41.7 13.40 1 0. 19 61.20 3. 10 0.80 2.4 83.36 5. 19 11.45 0.268 29 41.0 5.90 21.90 59.20 4.90 0.90 7.2 84.71 5. 15 10. 14 0.278 30 50. 1 17.70 21.20 55.90 3.20 1.80 0.2 84.79 5.09 10.12 0.290 31 25.9 18.80 13.95 49.50 9. 10 1.75 0.9 84.00 5.26 10.74 0.227 32 32.4 12.90 17.80 55.20 6.80 2.60 4.7 82. 12 4.97 12.91 0.250 33 52. 1 22.70 15.70 54.70 3.90 1.45 1.6 82.41 4.95 12.64 0.277 34 45.9 17.80 25.90 46. 10 8. 10 4.10 0.0 83.42 4.85 11.73 0.300 35 29.6 150 .1 24.40 48.20 3.10 2.80 6.4 83.20 4.97 11.83 0.255

S :sample, Cal.: calculated

76 TABL VARIATIO. E2 ASHF NO , WATER, IRON COAN ,I L

% wt average max min

0 3 ash 60 6

5 . 4 iro coan ni l 14.9 0.2

iron in ash 14 36 2

water 0.6 2.9 0.2

have shown that, Fe203 is the important factor causing errors in determinatio r f ashworkn o ou fino t t variatio.n ,s ou I d a . p f o n a resul f Fe20o t 3 variatio n ashi n , more samples shoule b d measured . 3. PROGRAMME FOR FUTURE

Shor1 . 3 t time interval measurements Wiegh r unipe tt are f coaao l changes rapidlmovine th n ygo bel. t Therefore, integration method of short time interval measurements shoul e use b dn orde i d o avoit r d h erroras n i s determinations, e.g. 0.2 sec.for KDCM, belt speed of which is 1.2 meters per second. Our count rate is about 6000 counts per sec., for wieght per unit area 2 f d thio abou an gr/c0 s1 t coun , m t 6 timerat s i es more than 5 countrate reported for KRAS-2 , for the same wieght per unit area. However, in the KDCM , we are have to measure count rates correspondin 2 3 o gt wiegh unir pe tt KRAS-r areafo e ( ,th 2 2 maximud suc gr/c5 an 2 ha hig) s mi m h wiegh unir pe tt arear fo , KDCM, may cause higher error which could be overcome by applying shorter distance between sourc detectord ean . on-lin2 3. measurementh eas s on-lin h measuremebtas e r gaugou ey b swil e arrangedb l , after gauge imprivement e completesar e laboratoryth n i d .

77 REFERENCES

1- Sowerby, B.D. (1991) Nuclear Techniques in the Coal Industry. In Nuclear Techniques in the Exploration and Exploitation of Energy and Mineral Resources. I.A.E.A. Vienna, 1991 proceeding a Symposium f o s . Vienna, June) 8 (5- , 1990.

- Abedinzadeh 2 Nucl. al .. et Geophys553. p . ,A , 4 . . VolNo , .7 (1993).

3- Gravi t is, V.L. et. al. Nucl. Geophys. Vol.1, No. 2, PP.111-124 (1987).

4- Fookes, R. A. et. al. Int. J, Appl. Radiât. Isot. Vol.34, No.l, PP. 37-44, (1983).

Thumme- Thir. 5 W . H d , lWorkin g Meeting, Radioisotope Application and Radiation Processing in Industry, held in Leipzig, ) sep27 .- 3 1985(2 , proceedings, 757 . Volp , , .3 (1986).

78 EFFECT HUMIDITF SO Y CHANGEN SO THE MEASURED CALORIFIC VALU COALF EO S

T. CYWICKA-JAKŒL, J. LOSKIEWICZ, G. TRACZ Institute of Nuclear Physics, Krakow, Poland

Abstract

The calorific value of coal can be inferred by different instrumental techniques. The simplest is to measure the ash content of the coal and use the evident link: low ash - high calorific value, high calorifiw lo - ch as values possibli t I . prompe e us als o ot t neutron-gamma activation analysis registering y-rays (4945 keV) from radiative capture on carbon. Here the cross-section is quite low for this reaction (0.003 barn). When using high energy neutrons from Pu-Be or Am-Be sources one can take advantag inelastie th f eo c scatterin f neutrongo carbon so n 12C(n , y)n' ,I2 C with 443V 4ke y-rays produced with cross-sections of 0.150 - 0.350 barn.

Key points studies in this paper are: the calorific value dependence on ash content and carbon content for coal; the influence of moisture content on the carbon gamma ray signal obtained from calculations; the experimental data on how carbon gamma ray signals change with rising moisture; the metho f correctindo carboe gth n gamm signay ara l usin hydrogee gth ngamma-countV 2.2Me 2 d san the possibility of analyzing coal for other elements.

1 Introduction.

The calorific value of coal can be inferred by different instrumental techniques. The evidene simples th - hig e measurh o t contenus th as s coa e linki d tas w th e an lf lo :e o th t calorific value, high ash - low calorific value. It is possible also to use prompt neutron- gamma activation analysis registering 7-rays (4945 keV) from radiative capture on carbon. Here the cross-section is quite low for this reaction (0.003 barn). When using high energy neutrons from Pu-Be or Am-Be sources we can take advantage of the inelastic scattering of neutrons on carbon 12C(n,n',7)12C with 4434 keV 7-rays produced with cross-sections of 0.150 -r- 0.350 barn. By far the largest part of our investigations was devoted to the last process. Its main advantage being the need for only moderately sized neutron sources (10 -=- 15 Ci Am-Be or Pu-Be source). In chapte stude w calorifie r2 y th c value dependenc contenh as carbod n eo an t n content for Silesian coals. In chapter 3 we describe the influence of moisture content on the carbon 7-ray signal obtained from calculations. In chapter 4 are described the experimental data whice carboth o hd n sho 7-raw who y signal change with rising moisture. Chaptes i 5 r devote e descriptioth o dt methoa f no f correctindo e carbogth n 7-ray signal usine gth hydroge 7-countsnV 2.2Me 2 chapten I . shoe possibilitw e w6 th r analysir yfo e coath s l for other elements. correlatioe Th 2 n betwee contenth nas , carbon con- tent and calorific value of coal.

There exists many empiric formulae, e.g. Dulong (1933), Grummel and Davies (Himus, 1946), which allow calculation e calorifith f o s c valu e mad b f coa o eo t el knowine gth concentration of elements such as C, H, 0, N and S.

79 e questio stronw Th ho thi s gi s ni s correlatio whad nan t dispersion will hav meae eth - surement points around stochastic calibration curve establishe thin di s wayr comFo . - pariso e correlationth n betwee contenh as n d calorifian t c valu s beeeha n studiede th : correlation coefficient shoul negativee db . These studie s beesha n conducte coaln do s from different part f Uppeso r Silesian coal basi whichusuan e no th y l b ,analytica l method e carbosth n concentration contenh as , t and calorific value were measured (Mielecki,1971). The parameters of a regression line:

Y(x) G= O+ s correlatioit n coefficient:

2 +

dispersioe th d an n about this line (standard deviatio spreae th f thesf no do e points): were calculated. 1 Her value eth Ys ei Î from regressio experimentae th - ny, lind ean l valuex : is either C - carbon concentration or A - ash content, ao and a\ are constants determined leasy b t square spreaS s RM methodd e abouth regressioe y th S t, numbee nth lines i N r, of point value ii_d th s/Studenf an s 2 ei o t distributio significanca r nfo e leve. a l

In Tabla e 1 these parameters are presented for the dependence of calorific -value on carbon conten r differenfo t t part f Uppeso r Silesian e Lublicoath r l fo nbasi regiond nan . e samTh e dat s beeaha n use determino dt dependence eth f calorifieo ch valuas n eo content. The results are shown in Table 2. Figures 1, 3, 5 and 7 show the sets of calorific valu correspondin8 s carboe v d an n6 conten, Fign 4 i , 2 sd g an plott r dependencsfo f eo calorific value on ash content. s veri t yI clear from both table d figurean s s thae spreath t f pointo d s aboue th t regression lines (whictakee b s stochastin na h ca c calibration curve smals i ) r calorififo l c valu carbos ev ntime8 content4. o s t sprea e smalle2 Th 1. . s di r tha Q=Q(A)r nfo : i.ee .se Table 3 This RMS spread Sy depends on three factors: e standar1Th ) d deviatio methoe th f no measurinf do e calorifigth c value. standare 2Th ) d deviatio methoe th f no measurin f do contenh gas r carboo t n concen- tration. n inheren3A ) t varianc e methoth n f eo calculatindo frogQ m known valuer o A s whicC s dependeni h n locao t l fluctuation e chemicath f o s l compositio d physicaan n l propertie f coalso .

!The confidence interva singla r ' valulfo eX measuremenw e shoulne a t calculatee a d b Y f to d (Natrella, 1963) as:

N £(*,-ä whereas error of estimation of the stochastic calibration line is

1 ( ' — rl2 : VC-" / ; ,1^ "* x r27 —'7 \ i Ft

80 Table 1. Parameters of a regression line for air-dried coals from various mining regions.

Y(x) = Q(C]

Region N aS aî R sf* Bytom 470 -343.97 97.91 0.995 72.44 Katowice 299 -213.71 96.26 0.988 77.53 Dabrowa 113 -112.97 93.89 0.985 85.00 Zabrze 454 -128.24 95.45 0.984 114.66 Jaworzno 279 -181.74 95.88 0.995 75.09 *kcal/k- g Lublin 769 66.16 96.02 0.969 169.83 - kcal/kg-%f C

Tabl . Parametere2 regressioa f o s n linr air-drieefo d coals from various mining regions.

Q(Ä)= Y

Region o(A). N a0 aî R •V Bytom 470 7468.00 -89.05 -0.883 350.88 Katowice 299 7453.13 -86.24 -0.876 241.36 Dabrowa 113 6811.08 -81.40 -0.923 187.26 Zabrze 454 7791.60 -89.96 -0.956 189.04 Jaworzno 279 6932.73 -75.50 -0.883 340.73 * - kcal/kg Lublin 769 7483.32 -84.92 -0.958 198.19 f - kcal/kg-% A

Table 3. Deviations from a stochastic calibration curve for the dependence of calorific value on carbon and ash conten theid an t r ratio.

cC 04 Mining region ÙY by Sy/Sy Bytom 72.4 350.9 4.84 Katowice 77.5 241 3.1 Zabrze 114.7 189 1.65 Jaworzno 75.1 341 4.5 U.S.A. 304 1070 3.5

81 writew no W:n eca

where 10; are unknown weights. Initially we can put tUj = 1. If only one component is used as the indicator of calorific value, it is natural that variation e amountth n i s f otheo s r components must chang e calorifieth c r valuefo , If . example constana t a , t contenh valuas f coae eo th t l show highea s r moistur lowed ean r

concentration of hydrocarbons then its calorific value changes (decreases). Therefore, for a good determination of the inherent variance of the method

3 Calculations of the influence of moisture content on 4.43 MeV carbon 7-ray signal yield for differ- t sourcen e detector spacings.

The aim of these calculations was to show the influence of changing moisture content on the 4.43 MeV7-ray flux from the 12Cr(n,n'7)12C reaction. Thus a good description of neutron interactions with nuclei of the coal substance is important. The precise mapping e geometroth f f measuremenyo f onlo s yi t minor significanc e sensitivitth r efo y studies. Therefore simple decideth e e w , eus one-dimensionalo dt Discrete Ordinates Code ANISN (Engle,1967) thin I .s progra e Discretmth e Ordinates method , togetheSN , r wite hth Finite Differences method make it possible to solve the Boltzmann equation for source neutron 7-rayd san s produce angular-spatian a n di l mes cellf ho s into whic materiae hth l is divided. The geometry was taken as a 17 cm or 31 cm radius sphere filled with different types of coals. At the centre of the sphere was positioned an 241Am-Be neutron source emitting n/s 1 spectrue .Th divides mwa d into energy groups correspondin DLC-7e th o gt 5 BUGLE (Roussin, 1985) structure. In the centre of the sphere either the 7-ray detector was placed wit efficiencn a h e 7-rayth takee r 100yb o %fluxeo nt s through spherical surfacef o s particular radius were calculated shows wa t nI . tha erroe th tf suc o r approximation ha n of real cylindrical one is < 15%. Typically, Polish bituminous coals have a moisture content of 2 -f- 8% in "air dry" state. Lignites show much higher wate r eve o conten 0 n4 60%, 30 t. The cross sections from DLC-75 (obtained by kind help of RSIC Oak Ridge National Laboratory, U.S.A. e mixear ) d accordin numbee th o gt e prograf atom o rth y F sb mGI (Group Organized Cross-Section Input Program prepared an ) r ANISdfo N e useth n .I ANISN calculations 31 discrete values of radii were taken (1 cm mesh) and Sg angular approximation were used. A maximum of three scatterings were permitted. As a result, we obtained a 7-ray flux of 7/(cm2 • s • MeV • Ineutron) in different 7-ray energy groups. The spheres were taken as consisting of the Janina 118 coal type with a moisture content of 12 %. The Am-Be neutron source was placed at the centre of the sphere. The 7-ray fluxes through spherical surfaces of variable radius are calculated for 7-rays from hydrogee th n (2.22 carbod MeVan ) n (4.43 MeV) nuclei resule Th .thesf o t e calculations

82 coam c l 1 spherseee 3 b e fonn th rshows tha e i ca carboe t th I tFig n ni . 9 n. 7~ray signal is rising in the region nearest the source, and for distances larger then 12 cm it is almost constant with materiale deptth n hi , wherea hydrogee sth n signa mors i l e significant a t large distances. The reason for this behavior is that the carbon 7-rays come mainly fro e firsmth t neutron collision, becaus f higeo h energe thresholth f yo d energe th f yo 12C(n,n'7)12C reaction (4.8 MeV), wherea hydrogee sth n generate e 7-rayb y w lo s ma y db energy neutrons e hydrogeTh . ntakee a rougb signa s y na hma l measur e wateth f reo conten coale th .n i t The results of the 7-ray flux calculations for the 17 cm radius sphere are presented in Fig.lOa. Here the results are more favorable for measurement, as the 7-ray signal from carbo stronges ni r already than this from hydroge r almosnfo l positional t e th n i s material. The distance from the centre of the sphere (where the source is positioned) to the spherical surface, considered as a "shell detector" where the 7-rays are counted, represents a rough approximation of the source-detector spacing. Therefore, to achieve a good signal-to-noise sense ratith n eoi mentioned earlier shora , t source-detector distance shoul usede db . If the moisture content of the coal is increased to 20 %, the calculations show a dramatic chang 7-rae th f yeo flux behavio radiusm spherc e 7 th 1 f , rf o e wheo n compared to Fig.lOa. This case is presented in Fig.lOb. The 7-ray signal from hydrogen is stronger than from carbon for distances > 4 cm, in contrast to the situation with 12 % moisture. Thus, comparing the behavior of the 7-ray fluxes in Figs 9, lOa and lOb, we easily come to conclusioe th n tha sample th t e size shoul kepe db t reasonably small thesl Al . e calculations show tha backgroune th t d from slow neutron interaction smals si lsampl e onlth f yi e size and source-detector distance is kept small. Therefore small sensitivity of carbon 7-ray signal yield on moisture content can be achieved onl smalr yfo l source-detector spacing smald san l sample sizes. Both these con- ditions can not be met in a realistic experimental arrangement. Therefore other method of solution should be devised. experimentae Th 4 l data concernin change gth f eo carbon 7-ray signal with rising moisture.

The threshold of the 12C(n,n',7)12C reaction is ~4.8 MeV, therefore neutrons of energy necessare ar V >4. 7~ragiv8Me o yV 4.4 t e eth y3 Me signal neutroe Th . n spectrum becomes depte softeth penetratiof s ho a r hydrogenoue th n ni s material increases. Thus, lesd san less inelastic neutron scatterings occur.

We use experimentae dth l arrangement presente Fig.lln di Pu-Be Th . e source uses di emitting 1.02-10 6 n/s. The source-detector distance is 41 cm. In Fig.12 is shown a typical observed spectrumseee b nn tha 7-raca e t th tI . y backgroun fairls di y larg thad e ean th t hydrogen pea mucs ki h more distinct tha carboe nth n peaks. In orde evaluato t r e influence th humidit e th e detectof th o e n yo r count addee w s d small amounts of water to bulk samples. The coal samples were previously ground to ~15 mm size. The bulk sample was mixed with additional water in a mixer, loaded into the measuring vessel and the 7-ray flux was measured using the Super-Ace plug in MCA (from EG&G d PC/Aan ) T computer. After mixing, samples weightin e kilograon g m each, were collected fro e bulmth k sample e wateTh . r conten thes wa nt determiney db weightin dryind gan procese t 105gTh a . addinf C °so g wate repeates rwa x eacr si dfo f ho samples until wate visibls surface th wa r n f coaeo eo l grainvessele th n si . This situation

83 r differens observefo wa % 22 t d coad betweean l samples% n~8 e 4.4 7-raV Th 3.Me y peak area (background subtracted calculates )wa d usin Maestre gth prograI oI m supplied wit MCAe h th show e ar Fig.lSn dependenc.e I b n th d aan carbonf eo 7-ray signal versus moisture conten Miechowicd r Janinan fo t 3 a20 e samples e decreasTh . carbon ei n 7-ray signal is marked and amounts here to a = 2.4 -f- 2.9 % per one percent additional water. In the Table 4 are presented the coefficients of the linear regression:

C-Y are the 4.43 MeV 7-ray counts, W - moisture content (weight %), b\ and 60 coefficients;

A$= ) a value/($ alss e i shownAW oe coal^ th y • 7-ra s sar i W dr A ,- r y $ ,ai flur xfo T

th7 e moisture change and A$-y is the 7-ray flux change. It can be seen from the table that the correlation coefficients are high meaning good description of the underlying physical phenomena. Also the values of the standard devi- experimentae th atiof o nS l points abou regressioe th t n line:

N-2 value th (hers ei i froeY m regression experimentae lineth ; y , numbee th s i l rN valu d ean of points reasonable ar ) y small correspondin carbof o r e.g.% gfo n ~2 7-raSiersz o t 5 y a70 signal. The rate of change a of the carbon signal with changing water content of coal is variable in the limits between roughly 1 4- 3% signal change per one percent of additional water. This fac askins i t r somgfo e typ remedyf eo . hydrogea f o e us n e signaTh correctin5n i l e gth carbon concentration from 12C(n,n',7)12C reaction in coal.

l neutroInal n method hydrogee sth n conten materiae th f o t l under investigation plays

an important role due to the hydrogen large slowing down power. In calorific value

12 12 measurements of coal based on the measurement of thCe12 isotope using thC(n,n'7)e C reaction (Stewart,1967; Sowerby,1979; Gozani,1984; Loskiewiczei.o/.,1992) high energy neutrons mus usee b t d becaus threshole eth thir dfo s reactio ~4.s ni 8 MeV neutroe Th . n spectrum becomes depte softeth penetratios f ha ro hydrogenoue th n i s material increases thereford an e less inelastic scatterings occur r compensatioFo . f thino s phenomenoe nw can use the radiative capture of neutrons on hydrogen which produces a well visible 2.22 7-ra measurusea e b s watee yda n th peak ca f ero t I conten. e f coathud th o t s an la s correcting e carbosignath o t nl measurement. This last measurement e neutroth s a , n spectrum is becoming softer as the water content rises, shows a decrease of 7-rays from inelastic scatterin f neutrongo carbon so n with rising moisture content. The carbon 7-ray (Cy) and hydrogen 7-ray (H^) signals were experimentally measured for each sample and at each moisture change. Then the cross-plots Cy versus H^ are drawn. In Fig.l4a, b and c are shown the plots for Janina 116, Bobrek 783 and Miechowice samples e Table showth ar e n characteristiceI 5 th n. versu , C~ ^ regressio H se th f o s n

linese linearit e dependencTh . th f yo f(H^= y quits eC i ) e e correlatioevidenth d an t n coefficients high excep Janinr fo t wher8 a11 e some instabilitie arises sha n when measuring the points in the low moisture range.

84 Using these result cane sw orde n ,i obtaio t r nbettea r carbon content estimate construct a correction formula of the type:

where:

(7-Y correcte- 0 d carbon 7~ray signa t initiaa l l humidit mediastatee y 0 (e.g.th ydr k r r o , ai n h value)

(Zy actuall- fe y measured carbon 7-ray) humiditsignae ho th > t a lh ( yh H^ - hydrogen 7-ray signal at the humidity ho (to be determined during calibration)

H^h - hydrogen 7-ray signal at the humidity h (the value of humidity must be known only during calibration)

For the Janina mine we used three samples which correspond to three different seams. The ci coefficient for these seams varies between 0.060 and 0.079 with the mean value of 0.06 90.0096.± correctio n this a tryine A whics f si o ar e e correco ght w us n e factoth ty b r 7-rae th y signal changes amountin ±13o gt % (fro middle mth e value humidity)f so , thus

Tabl . Characterisite4 regressiof co n lines (C~, moisturs hv weight)y eb .

Sample r bo bi S a AW code correlation counts counts/ spread about % signal ch./ % water coefficient % water regression line % water ch.

3 Siersz5 a70 -0.91 90-10 -1140 1690 1.46 8.1 Janina 118 -0.97 145-103 -1530 1900 1.07 6.0 Janina 203 -0.98 103-103 -1880 1630 2.38 8.9 Bobre3 k75 -0.80 113-103 -3040 4270 2.93 4.6 Miechowic2 e81 -0.99 101-103 -2570 1200 2.70 6.4

e parameterTablTh . e5 e regressio th f so i n C C line= Q + ^ sC

Sample code r Cl Co S %C correlation count7 / sC counts spread about coefficient count7 sH regression line

Siersza 705 -0.93 -0.0433 41Û • 5 11 1500 62.7 Janin8 a11 -0.77 -0.0675 254 • 103 7290 65.0 Janina 203 -0.997 -0.0793 010 • 8 14 645 61.4 Janin6 a11 -0.93 -0.0598 126 • 103 2060 65.5 Miechowic2 e81 -0.98 -0.115 189 • 103 1530 70.2 Bobrek 753 -0.96 -0.0789 174-103 1940 74.4

85 this spread will introduce roughl erron ya f leso r s than 1.8e finath % ln i assessmenf o t carbon concentration. We can approximately count with 6-=-7 times smaller measurement uncertainty than withou correctione th t realitn I . variatione yth coaf so l humidite th n yi s received"a " stat e mucear h smaller tha e fulnth l possible rang f humidito e y change availabl laboratorye th n ei . Therefor carboe eth n 7-ray signal change wil smallee b l d an r the error of the correction also. These problems are now under assessment. It is well known (Stewart,1967; Sowerby,1979; Cywicka-Jakielei.a/.,1984) that there ilineaa s r dependenc carboe th f eo n concentratio e carboth n no n 7-ray signal face Th t. tha carboe th t n concentratio gooa s ni d measur calorifie th f eo c coavalue bees th ha lf neo showr earlieou n ni r papers (Cywicka-Jakielei.a/.,198 1991d 4an ) also. It is illustrated on Fig.7 where it is shown for the region where Janina and Siersza mines lay.

6 Possibilities of registering other elements in coal using Pu-Be neutron source.

The Pu-Be (or Am-Be) sources produce a neutron flux which spectrum extends well into 6-7-8 MeV range. This spectrum contains also lower energy neutron which when slowed usee b dowPGNAr dn fo nca A (radiative captur slof eo w neutrons) problee Th . mthas i t neutroe th n sources used here produc emuca h lower neutron fluxes than used normally for PGNAA and not all normally detected in PGNAA elements may be analyzed. contenh foune as infe d W moistur d e measurn an dth an rt , ca tha e Cl , w t eeSi content shows i 2 7-rae 1 nth valuesg y Fi spectru n I Bobree . th samplr 3 mfo k79 e i wherS e eth (1.78 MeV), hydrogen (2.22 MeV) peak wele ar s l visiblee Figur s showth i n 5 I e .e1 nth spectru e samth f meo coal with NaCl added. Her e 6.1chlorinV eth 1Me e pea wels ki l visible iroe nTh . (7.6etc.V 4)Me peak comine sar g mainly fro r experimentamou l setup which contains large amounts of iron. We have mad ecruda e assessment measurinf so g error obtained san d following values:

Calorific value (50 ^ 75% Cj Using onl 7-rayy C MJ/k 5 0. s g with corrections <0.1 MJ/kg Ash h 1.1as % weighy b 90 h rang- t2 1 e h <0.5as % %28 weigh y h b - 1 1 t Moisture rang wate % H2 e1 -21 weighy b r t 0.3-r-0.7 weighy %b t for particular mine Chlorine 0.09% Cl by weight 0.07% Na (unde fore r th f NaClm assumptioo n i s i ) l C l nal Silicon (SiOi) better than 1.0% by weight All these value obtainee sar r coaldfo s from single mine. Reassuming these results show the possibility of constructing a quite precise calorific value meter with some potential for measuring ash, moisture and silicon and chlorine. sodiue Th m assessecontene b y ma dt under assumption tha fore l sodiuth al f t m o n i ms i NaCl.

86 This work has been funded by the IAEA Research Contract 5807/RB and the grant from Komitet Badan Naukowych (Poland) N°202609101.

34 8000

32 N=470 points

30 ai-0.410[MJ/kg%C] ao-1 .440[MJ/kg] 7000 28 <&>~0.037[MJ/kg] *70.36[%C] 26 =27.403[MJ/kg} O> R=0.9953 «000 == 2 24 U IB 22 IQ 5000 5 O 20 U o 18 £ « CO Ü 4000 U 16

14

3000 12

10

20 30 40 so en 70 BO 90 % C (by weight)

Flg.1 Calorific value vs carbon content for By to m region.

34 8000

32 N=470 points

30 at-0.373[MJ/kg%ash] ao-3f 267[MJ/kg] 7000 28 <&>-0.17S[MJ/kg]

0> 28 =Z7.403[MJ/kg] 6000 ^ 24 U

22 n 5000 « 20 _o _ n 18 o Ü 4000 O 16

14 3000 12

10

10 20 30 40 50 60 Ash content [%]

Flg.2 Calorifi cconten h valuas Bytor s ev fo t m region.

87 32 N=299 points Y=atx+ao ai-0.403[MJ/kg%CJ ao-V.89S[MJ/kg] <&>-0.049[MJ/kg] 7000

,—. 28 *72.01 [%C] O) =28.126[MJ/kg] O) ^ R>*03880 "5 l 26 u

O 6000

l 24 ~m o 22 rt O o 'S 5000 20

18

4000 16 40 50 60 70 so SO weighty (b C }%

Flg.3 Calorific valu carbos ev n conten Katowicr fo t e region.

32 N=299 points y=atx+ao 30 ai -4.361 [MJ/kg %ash] ao-31 £05[MJ/kg] >-O.f =28.1 26 [MJ/kg]

26 6000 at > 24 a t3 5S

O 1 a Ü Ü 5000

20

18

4000 16 20 30 40 Ash content [%]

Flg.4 Calorific conten h valuas r Katowics ev fo t e region.

88 35 N=454 points 8000 33 Y=aix+ao ai"0.4QO[MJ/kg%C} 31

<&>-0.059[MJ/kg} 7000 29 =7134[%C] =2ff_2r 2[MJ/kgJ o>

I 25 6000 .K O ffl W 23 "5 U £ 21 5000 je

_0 co 3 ü

17 4000

15

13 3000

11 50 80 70 BO % C (by weight)

Flg.S Calorific value vs carbon content for Zabrze région.

35 8000 33 N=454 points y=ax+ao 31 ai-0.377[MJ/kg %ash] eu>-32.622[MJ/Kg] <&>~0.097[MJ/>

O> =28£1 2lMJ/kg] ^ 27 CO I . aooe j û o ffi B 23 et

5000 =

19 3

17 4000

15

13 3000

11 10 20 30 50 60 Ash conten] t[%

Flg.6 Calorific value vs ash content for Zabrze région.

89 32 N=279 points 30 Y=atx+at> at-0.401 [MJ/kg16C] 7000 ao-0761 tMJ/kg] 28 <&>-.050[MJ/kg] =& .42[%C] CO 2« =23.894iMJ/kg] R~0.9946 6005 7 0 :£

~- 24 O a > 22 Ü I sooo € 20 _ n Ü Ü 18

4000 18

14

30 40 50 60 70 80 % C (by weight)

Fig.7 Calorific value vs carbon content for Jaworzno region.

N=Z79 points 30 y=atx+aa ai-4.316[MJ/kg%ash] 7000 ao-29.026[MJ/kg] 28 =1 6.23[%ashl 0» 26 °23.a94[MJ/kgl 6000 70 U J£ _ 24 O O "5 15 > 22 O sooo —

4000 16

14

20 30 40 so Ash content [%]

Flg.8 Calorific conten h valuas Jaworznr s ev tfo o region.

90 020 JANINA118 12%HA (r-31cm)

0.18 Carbon-*- f-ray peak 0.16 -•- Hydrogeny-raypeak

± 0.14

> 0.12 CD •S! 0.10

V 0.08 CM

"* 0.06

0.04

0.02

0.00 12 18 20 24 28 Radius r [cm]

Flg.9 Hydrogen and carbon y-ray fluxes passing through spherical surfaces for Janlna 118 coal sample (r=31 cm) with 12% water added.

0.030

0.026

~ 0.020

M 0.016

0.010 (r*t7cm)

-*- Carbons-ray peak 0.006 -•- Hydrogens-ray peak

0.000 8 10 12 14 16 18 Radius r [cm]

Flg.1 Oa Hydrogen and carbon y-ray fluxes passing through spherical surface Janlnr sfo coa8 a11 l sample (r=1 watewit) % h7cm 12 r added.

91 0.06 JANINA118 (r~17cm)HzO 20%

0.05 Carbon f-ray peak Hydrogen y-ray peak

0.04

°-03

0.02

0.01

0.00 B 10 12 14 16 18 Radius r [cm]

Flg. Hydrogeb 1O carbod nan n y-ray fluxes passing through spherical surfaces for Janlna 118 coal sample (r=17 cm) with 20% water added.

0350 01bO 1 "ß12Ö~

t A! pipe

^~-^ Steel container

Coo! sample G><* <3& Q$- Neutron source ~O\~> • —— ^ & ^\ //// ^ ~^c? c? c? O> O> (~-> Pb shield (o cm) & v m O- r^ ^^ c\

. 4ääk c=a " —— ~~ ~G >- > *& ~~~- ^010'.rr ) x -10c1 ( J mNa Detector 1 U

c

Fig. 11 The experimental setup.

92 H V 2.22Me sample BOBREK 753 500000 I S vV 1.7Me 8. detector Nal(TI) o

400000

o u \ 15 c ce 300000 v -c ü k. 0 CL U 200000 uO

100000

too 150 200 250 300 350 channel number

Flg.12 Measured y-ray spectrum from Bobrek mine bulk sample.

100000 JANINA coal203 sample water+ O9 J£ 4x4 In NalfTI) detector o 20 h - live time 03 6 o 80000 Pu-Bo 1,02*10n/s

09 c aoooo o o

« 70000 l ü i co 80000

50000 S I 8 1 7 1 13 6 1 5 1 20 Moisture content [wt. percent]

Flg.13 dependence aTh f carboeo n y-ray signa moisturn o l e content r Janlnfo sample3 a20 .

93 110000 M1ECHOWICE coal sample + water at J£ 4x4 NalfJI)in detector o live- 20 h time TO e O 100000 Pu-Be 1.02x10 n/s

O

s oooo O U

80000 - Ü

ID

CO 70000

60000 B 7 « 5 4 3 2 Moisture content [wt percent]

Flg.13 dependence bTh carbof eo n y-ray signa moisturn lo e content for Mlechowlce 812 sample.

100000 S JANINA118 coal sample water+ NaKTI)In 4*4 detector 20 h - llvo time 90000 Pu-Be 1.02X10*n/s

g «0000

ï • * «coo

60000 eo

50000 flOOOOO 000000 1000000 1100000 hydrogeV Me 2.22 n y-ray (net counts)g k norm 0 3 o ,t

Flg.14a The cross-plot of carbon y-ray signal versus hydrogen y-ray signa Janlnr lfo sample6 a11 .

94 110000

o CO o 100000 o

o o 90000 a>

BOBREK (duplicata) coal sample waterf - 80000 4*4 In Natfri) detector .§o 20 h - live time A Pu-Be 1.02x10* n/s u

70000

60000 «00000 800000 1000000 1100000 1200000 2.22 MeV hydrogen yray (net counts) norm, to 30 kg

Flg.14b 4.43 MeV carbon peak area changes vs 2.22 MeV hydrogen peak area for Bobrek 753 sample.

110000 MIECHOWICE coal sample water+ O CO 4x4 In NaKTI) detector 20 h - live time e 100000 Pu-Be 1.02x10 n/s

uO 90000 tt>

C

80000 O JQ cB O

O 2 70000 m

60000 800000 900000 1000000 1100000 2.22 MeV hydrogen y-ray (net counts) norm, to 30 kg

Flg.14c Carbon y-ray signal versus hydrogen y-ray signal for Mlechowlc sample2 e81 .

95 5000000 2.22 MeV H X10 X15 in ö

—' 4000000 O OJ i u 3000000

o 5 2000000 CD Q.

g U 1000000

100 200 300 400 500 channel number

FIg.15 Measured y-ray spectrum from Bobrek mine bulk sample with NaCI added.

REFERENCES

Cywicka-Jakiel T., Bogacz J., Czubek J.A., Dabrowski J.M., Loskiewicz J. and Zazula J. (1984), "On the measurement of specific energy of coals by means of 12C determination usin gcorrelatioa n method", Int . ApplJ . . Radiât. 7 Isot. , 35 ,

Cywicka-Jakie , Hajda Loskiewicld T. an , sI . (1991)zJ , "Statistical comparisoe th f no accurac f nucleayo r method measurinr sfo calorifie gth c value coals"f so , Görnictwo Polishn i (Mining) , 3 1 . , 15 , Dulong P. (1933), Fuel 12, 199. Engle W.W. (1967), "A user's manual for ANISN", ORNL Report K. 1693.

Gozan . (1984)T i , "Physic f receno s t application f PNSo s r on-linAfo e analy- f sibulo s k materials" n SymposiuI , n Capturmo e Gamm y SpectroscopyRa a , Knoxvill. Inst f PhysicsAm o . , eTN , p.828-846. s citea Himuy db s G.W. (1946), Fuel Testing Methuem London.

Loskiewicz J., Cywicka-Jakiel T. and Tracz G. (1992), "A computer assessment of e influencth f humidit o e contenh e calorifias th d n o tyan c valu f Poliseo h coals.", Nucl. Geophysics , 1916 , .

96 Mieleck . (1971)T i , Monograp f Polisho h Goals, Ser . 1971M . polish)n ,(i G GI . Publications, Katowice.

Roussin R.W. (1985), "BUGLE80 RSIC Data Library DLC-75", Report ORNL ANS-6.1.2.

Sowerby B.D. (1979), "Measuremen f specifio t c d moisturenergyan h as buln ,e i k coal sample combinea y sb d neutro gamma-rad nan y method.", Nucl. Instr. Meth., 160, 173.

Stewart R.F. (1967), "Nuclear measurement of carbon in bulk materials", Instrum. . Trans.SocAm , .200 6 , .

97 COA PARAMETERH LAS NATURAY SB L RADIOACTIVIT NEUTROD YAN N ACTIVATION

E. CHRUSCIEL, S. KALITA, J.L. MAKHABANE, A. LENDA, NGUYEN DINH CHAU, J.W. NIEWODNICZANSKI, K.W. PALKA Facult f Physicyo Nuclead san r Techniques, Universit f Mininyo Metallurgyd gan , Krakow, Poland

Abstract Natural radioactivity of 400 coal and sedimentary rock samples, collected from cores of the wells drilled in the Upper Silesia Coal Basin, has been measured in order to determine the uranium, thorium and potassium concentrations with the use of a scintillation gamma- ray spectrometric system determinee Th . d concentrations were use identifo dt e yth lithology of the rocks and evaluate the following hard coal parameters: ash content, calorific valu carbod ean n content. contenh meae as Th e nth t standar betweer fo , % nd % 2-3wt deviatio t 3 w 5 1. f o n 1.3 MJ/kcalorifie th r gfo c value betwee carboe th r nnfo 17-3% t 2w 5 MJ/k2. d gan content between 43-7 wer% 2wt e obtained. Feasibility of determination of the ash content and the ash fusion temperature via the neutron activation techniqu s beeha en examined e laborator,th bot n i hd fiel an yd conditions. The technique is based on recording induced gamma- ray intensities in two energy intervals with the help of a scintillation gamma ray spectrometer. In laborator weln i d l yloggingan meae ,th n standar, °C d 5 deviation3 d an % st werw 5 e1. , respectively°C 5 4 d an . % t anw d3

•[.INTRODUCTION

Coal is a complex, stratified and heterogeneous organic rock formed by partial decompositio planf no t matter manr Fo . y purposes consideree , b coan ca lthre a s da e component mixture consisting of organic substances, mineral matter and water. The mineral componen bituminouf to s coal occur organin si c component ash, inherend an h as t dirt bands. The major elemental constituents of mineral matter are Si, Al, Fe, Ca, Mg, K, Na and S; , Cd , Li e trac, minoth B e , eth d P etc, element, an r.Pb constituent , Mn Cl e s, ar Ti e sar U, Th, Gd, etc. The total sum of minor and trace constituents of mineral component of coal amounts to 2.0 wt %. It has been confirmed that all types of coal occur in the Upper Silesian Basin: sub- bituminous coal, bituminous coaantracite.Thd lan e analysed coal samples were retrived from different mines and exploratory boreholes in the Upper Silesian basin. The ash content of the samples varied between (1.5- 40) wt % . elementae Th l concentrations (major constituents analysee th f )o d coal samples vara n yi rather wide range. This explains the fact that the coal parameters have a local character. Result e chemicath f so l analyse e corth ef so samples from different boreholes were investigate n ordei d o establist r h possible statistical correlation existin r differenfo g t coal quality parameters (Chruscie [4]). al .t e lTabl showe1 s correlation betweee nth following parameters: calorifi ccontenh valuas , , moisturQ etA e contenfusioh as , ntW

99 temperature t, carbon concentration C, hydrogen concentration H, and concentrations of SiO, AI O, Fe O and MgO represented as Si, Al, Fe and Mg, respectively. The correlation coefficient everr sfo y relatiomeae th d n nstandaran d deviation alse sar o given. In this work R is a multiple- correlation coefficient between the measured and fitted x- values, (where x = A, Q ...), and is an arithmetic mean standard deviation for prediction of a given x value (calculated as representative for the whole range of measured quantities).

2.EXPEREMENTS

2.1. Natural gamma- ray 2.1.1.Laboratory measurements About 400 bore-core samples (193 coal, 130 shale, 52 mudstone and 14 sandstone) each weighing about 0.6-1.2 kg, were crushed to a grain size below 2 mm and sealed for 1 mont n orde(i h achievo rt radioactive eth e equilibriun i ) Bi m d betweean a R n marinelli type aluminum containers of a fixed volume. The detector scintillation crystal places wa d symmetricall sample th yn i e container thicknese Th fron. e laterad th an tf so l samplelayers sely surroundinfan absorptioo s , crystae mm g equath s n0 2 effectlwa o lt s could be neglected. The grain size in each container was kept almost constant, although the size distribution was unknown and the packing density was not controlled. The coal sample calorifie th s , wer %) ckJ/kg n t i value contenw , h analysen as i (Q e) , e th t(A r dfo classicae th ancarboe y b d th ) l % n methodt contenw n i , s t(C accordin e Polisth o ght National Standards. Gamma-ray detection system consisted of a 3" by 3" Nal(Tl) scintillation crystal coupled to a 1024 channel pulse height analyser. A gamma-ray shield was a 10 cm lead, 10 mm iron, 2 mm copper and 2 mm cadmium housing. In the scintillation spectrometric measurements the following three energy windows were applied: 1.36- 1.54Me , 1.66^K) V( - 1.86Me uraniu, Bi ( Vm series) and 2.4 H-2.8 MeV (Tl, thorium series). By measuring gamma-ray spectra in the calibration samples and using the techniques discusse Adamy db Fryed an s r [1], Lenda[8] ,on n establiseca e th h dependenc e intensitieth f o e s registere three th en di spectrometer windowe th n so U,Th and K concentrations. The detection limits for a 100 min counting time were equal to about 0.02 % K, 0.14 ppm U and 0.5 ppm Th (Chrusciel et al.[4], Kalita et

2.1.2. Borehole measurements A borehole gamma-ray spectromete bees rha measurementn e useth r dfo modele th n si s of radioactive rocks existing at the Enterprise of Geophysical Prospection in Zielona Gora. The models are five cylindrical, concrete pits with different admixtures of radioactive elements.The diameter of each pit is equal to 2 meters and the height equals 2 meters.Each model contains three measuring holes, paralle cylindee th o t l r axis with diameters equal to 90, 160 and 220 mm, respectively. By measuring gamma-ray spectra establisn modele ca ith n e dependence shon th intensitiee th f eo s registere three th en di

100 spectrometer windows on the K, U and Th concentrations. An adequate computer software (KALEBR program) has been created.

2.2. Neutron activation technique 2.1.Laboratory measurements It has been stated by many authors that the neutron activation technique proved to be useiul for rapid assays of coal samples and evaluation of coal seams as a well-logging method. There is a good correlation between the ash content and principal constituents of ash - e.g. Borsaru and Mathew [2,3]; Clayton et. al. [5]; Makhabane [9]. As it has been stated by many authors, e.g. Winegartner and Rhodes [11], Borsaru et al. [3], the chemical composition of ash affects the ash fusion temperature. This dependence was tested for the same bore core coal samples which were used in the mentioned above studies fusioh As . n temperatur measures wa e Leitt th y zdb methos d(a the so-called hemi-spherical point determination). Laboratory measurements were performed using an activation and detection set-up describe Makhabany db e [9]e sample fixeTh a . f do sa volumf o d an e) (abou3 dm 1 t werg k mas e5 place1. s car a betwee d n ddi an boar 6 n0. d container, equipped witn ha annulu accommodato st neutroe eth n source, which aftee irradiatioth r replaces wa n y db NaI(Tlm m 6 7 ) x scintillatio6 a7 n irradiatio e crystalth r Fo . nthica k paraffin cylindef ro heighm usedc s neutroe 100 diametetwa m 0Th .15 c nd sourcan r Pu-Bs ewa e whose 6 neutrons/s10 yielabous x 5 wa d multichanne5. tA . l spectromete s adaptewa r o dt record gamma-rays in two broad energy channels, the first one of a 300 keV width for the 843 keV gamma-rays, and the second one of 500 keV width for gamma-rays from the 1780 keV region. The first energy window corresponds to the gamma-rays of Mg (843 keV), createe neutroth y db n induced reaction magnesiumn o s , aluminud man (84silicon 7M nkeVe isotopeth ) o t gamma-rayd san s which result from activatiof no stable isotope manganesee th f so , irocobaltd highene an Th . r energy window allowo t s recor gamma-raye dth l (177A 9f o skeV ) resulting from activatio aluminuf no m and silica isotope (181n thosd M 1s an f ekeV)o . The sequence of activation, cooling and counting procedure was as follows: 20 min. irradiation minute on , e coolin d 100 countinggs an 0 . A typical gamma-ray spectru coaa mf o l sample recorded usin scintillatioe gth n spectrometer mentioned above is shown on Fig. 1. The counts N! andN, corresponding to the lower and higher gamma-ray energy

interval normalized san a uni o dt t mass, 2 were then use construco dt t linear regression equations relating the Nj and N2 values to the ash content and ash fusion temperature. Borehole experiments were performed using a borehole scintillation spectrometer describe PalkaflO]y b d Po-BA . e neutron sourc yiel s separates n/ abouf ed wa o 7 10 t d Nal(Tl m spacinm m 5 0 )7 1. b gcrystalyx a fro5 3 loggin e ma ;th g velocit equas ywa o lt 1 m/min and the gamma-rays were detected in the same wide energy intervals as those adopted in the laboratory measurements. Net count rates were corrected for the natural background, and coal seam thickness. The last data were known from a natural gamma- ray log. The combined data from three logged boreholes, about 1.5 km deep each, which intersected more than 20 coal seams (for which the bore-core samples had been collected) were used to construct the regression equations for ash content and ash fusion temperature.

101 3.RESULTS AND DISCUSSION

3.1.Natural gamma-ray concentratione Th potassiumf so , uraniu thoriu d analysee man th n mi d bore-core samples showFig.2n i e nar . Generall presence yth potassiuf eo thoriud man coamn i l reflects the amount of mineral admixtures (clay, shale) within the coal sample. Hence, clean (low in ash) coals usually exhibit low concentrations of these elements. The concentration of carbon in coal, known from standard chemical assays, linearly decreases with the increase of uranium content, as shown in Fig.3. All these factors make possibl calculato e t content h as e eth , calorific valu coaf carbod eo lan n content usine gth dat potassiumn ao , uraniu thoriud man m concentration coaln si . Thi demonstrates si n di Table 2. The ranges of the coal parameters in the analysed samples were: 5-35 wt % for ash (A), 17-32 MJ/k calorifir gfo c value (Q)an carbor d fo 43-7 n% conten2wt t (C). The concentration demonstratK d an h T , differentiatioea s U variour fo n s rocks lithologies: e.g. mudstones and shales are much richer in thorium and uranium than coals and sandstones.The latter two rock types have, on the other hand, a markedly different potassium content. All these results suggest that the coal seams could be easily separated from the embedding rocks on a spectrometric natural gamma-ray log, especially due to uraniuw lo e mth content lithologe Th . determine e rockf b yo n sca d whee nth concentration radioélémente th l al f so takee sar n into account helpfue . e b Thi th n n si ca l identification of given stratigraphie layers in the lithologie profile. Such a conclusion can be drawn from Fig.4, where discrete results for K, U and Th concentrations are plotted for a 30 m long interval of a borehole, corresponding to the coal-bearing part of the profile spectrometrie Th . c gamma-ray data give more informatio deposie th n no t thae nth classical (total) natural gamma-ray log (GR) can be helpful in the identification of given stratigraphie layers in the lithologie profile. Such a conclusion can be drawn from Fig.4, wher econcentrationh discretT d an elonU resultm , g0 K e plotte 3 r intervas ar a s fo r dfo l boreholea f o , correspondin coal-bearine th go t profilege parspectrometrith e f to Th . c gamma-ray data give more information on the deposit than the classical (total) natural gamma-ra (GR)naturag ylo l gamma-ra (GRg ylo ) 150. 0C contenfusioh h as As d n temperaturetan , calculated fro neutroe mth n activation datd aan determine conventionay b d l laboratory analyse comparee sar , Figure6 n d i d an s5 respectively. resulte Th analogouf so s borehole measurement presentee ar s Tabl. 5 tablen d i ean s4 4 contains the regression equations for ash content and ash fusion temperature. These calibration equations were then used for determination of the ash parameters for other coal seams; some examples of confrontation of the logging results as compared with the ash parameters determined from core samples by conventional methods are shown in Table 5.

4.CONCLUSIONS

Experimental investigation naturaf so l gamma-ray spectra have shown that quantitative determination of the ash content, calorific value and carbon content by natural gamma-ray spectrometry was feasible. Natural gamma-ray measurement e carboniferouth f so s Uppee rockth f o sr Silesian Coal Basin have shown that the specific activity of shale and mudstone is higher than that

102 of bituminous coal. These observations can be used to identify lithology, to determine the thicknes e carboniferouth f so s separato layert d an s e dirt bands from coal during exploitation and processing. The natural gamma-ray log is relatively simple fast, inexpensive and more attractive thaothey an n r nuclear method sinc t doe i erequirt no s e applicatiof o n radioactive sources. The neutron activation technique proved to be useful for rapid assays of coal samples and for localization of coal seams as a well logging method. The obtained results demonstrate feasibility of determination of the coal ash parameters: ash content in coal and ash fusion temperature by the neutron activation method, both in laboratory and through borehole logging. lattee Th r application enable geologiste sth determino st e parametere coaf th s o s la industrial fuel at the early stage of evaluation of a coal deposit.

Table 1. Statistical correlation between concentration of main elements and parameters of coal.

Relation Correlation coefficient Mean standard R deviation o A=A(Al,Si) 0.95 0.7 wt % A=A(Si, AI, Fe, Mg) 0.99 0.5 wt% Q=Q(C) 0.98 600 U/kg Q=Q(A) 0.79 2100 kJ/kg 0=Q(A) ,W 0.97 400 Id/kg 0=0(A, W, C, H) 0.99 250 kJ/kg t=t(Si) Al , 0.76 38 °C t=t(A, Si, Al) 0.78 36 °C

Table 2. Coal parameters:ash content A (wt %), calorific value Q in (kJ/kg) and carbon content C (wt % ) as calculated from the results of the determination of uranium Cv (ppm ), thorium CTh (ppm) and potassium CK (wt % ) from Upper Silesia coal samples.

Equation Correl. coeffic. Mean stand, R deviation o

A = 3.27 + 21.36CK + 1.62 Cv + 0.61 C^ 0.98 1.2wt% Q = 2900 - 2570 CK - 1330CtJ + 95 C^ 0.89 1250 kJ/kg C = 72.69 - 4.75 Cy 0.97 % 2.t 5w

103 Tables. Regression equationfusioh contenas h d nas r an temperatur sfo tA efrot m d countan j sN N2 recorded after activation of coal samples.

Equation Correl.coeffic. Mean stand, R deviationa

A (wt %) = 4.02 + 6.47x10 N - 7.84x1! 2 0N 0.90 1.5wt% 0 t( C)=1216-0.003N!+0 045 N2 0.92 3C 5°

Table 4. Regression fusioequationh as contenh nd as temperaturr an sfo A t t froe m (normalized and net) coun 2 recorden d e tneutro an rateth j n di n s n activation borehole logging.

Equation Correl.coeffîc. Mean stand, R deviationa

A45.6= - 0.9j 4n - 0.28 n2 0.90 3wt% =1290t - 0.0! 8n + 0.17n2 0.76 4C 5°

Table 5. Comparison of ash content and ash fusion temperature in eight coal seams determined by laboratory conventional analysi corn o s e sample s(LA- calculated )an d fro neutroe mth n activation logging data - (NA).

Thicknes) s(m Ash content in coal (wt. %) Ash fusion temperature (°C)

LA NA LA-NA LA NA LA-NA 1.5 16.1 14.0 +2.1 1400 1370 +30 0.9 8.7 9.2 -0.5 1340 1380 -40 0.8 20.6 22.3 -1.7 1330 1300 +30 0.7 13.0 15.0 -2.0 1280 1340 -60 1.4 18.7 21.3 -2.6 1440 1400 +40 3.0 9.5 8.2 +1.3 1280 1260 +20 2.0 11.2 9.5 +1.7 1360 1350 +10 0.8 13.8 11.0 +2.8 1240 1290 -50

104 250

200

Lu 0 o 2 150 o < B3i* keV X U f to 100 o V 177ke 8 o 00 0*°

50

100 .200 300 400 500 600 700 800 900 CHANNEL Fig.I. Typical gamma-ray spectrum of coal recorded using scintillation spectrometer.

Fig.2. Concentratio thoriumf no , potassiu uraniud man Uppemn i r Silesia carboniferous rocks and their mean values for mudstone (M), shale (S), sandstone (St) and coal(C).

105 1.1 i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i t 11 i i i i i i i i i i 0.0 2.0 4.0 6.0 8.0 10.0 Uranium, ppm Fig.3. Comparison of carbon content and uranium concentration in Upper Silesian coal.

CPM Total count 0 80 100 0 0UO60 O

SANDSTONE COAL SHALE SHAIY CLAYEY CLAYEY SANDSTONE SANDSTONE SHALE Fi gTota4 l natural gamma-ra using ylo gnon-spectrometria determinece probth d ean d concentrations of K,U and Th.

106 3O

25

20

15 c v •*->c o ü 10 .c W 5.0'-

O 5.0 IO 15 2O 25 3O Ash content by ehem. lob. anal, wt %. Fig.5.Correlation between ash content in coal as determined by laboratory neutron activation analysis and by a conventional method.

1500

14Ï

o o 1400 -

1350 -

a. E ^ 1300 _o "

-C 1250 - M

1200 1200 1250 1300 1350 1400 1450 1500 Ash fusion temp y con.(Leitzb , ) method (*C)

Fig.o.Correlation between ash fusion temperature as determined by laboratory neutron activation analysi conventionay b d san l Leitz method.

107 REFERENCES

1.Adams J.A.S., Fiyer G.E. (1964). "The Natural Radiation Environment" (Eds Adam J.A.S. and Lowder W.M.) University of Chicago Press, Chicago, 577-596. 2.Borsaru M.,Mathew P.J.(1982).Fast neutron activation analysis of bulk coal samples for alumina, silic ashd aan . Anal. Chem. Acta 1142 S.Borsaru M., Biggs M.S., Nichols W.J.F. (1992) Neutron-gamma logging for the determinatio contene F f no n coati l seam implementationd san estimatinr sfo h as e gth fusion characteristics at Collide Mine. Paper presented at the IAEA CRP Meeting "Nuclear technique exploration si exploitatiod nan coal"f no , Ankara, Turkey Octobe9 5- , r 1992. 4.Chrusciel E.,Kalita S.J.L. Makhabane, J.W. Niewodniczanski (1992). "Natural Radioactivit Carboniferrouf yo s Bede Uppeth n si r Silesian Coal Basin. T ReporIN . tNo 258/1, Institute of Physics and Nuclear Techniques, Krakow, Poland. 5.Clayton G.G.,Hassan A.M.,Wormald M.R.(1983). Multielemental analysis of coal during borehole logging by measurement of prompt gamma-rays from thermal neutron capture. Int Appl. .J . Radiât. Isot. t.34, no.l. 231-260. 6.Kalita S.(1984). Determinatio naturaf no l radioactive impuritie somn i materialsw era s and building material gamma-ray sb y spectrometry. Repor 186/I,ThT tIN e Institutf eo Physic d Nucleasan r Techniques. AGH, Krakow Polisn (i , . h) 7.Kalit , ChruscieaS. , NiewodniczansklE. i J.W. (1988). Determinatio Yielh As n di f no Coa Naturay lb l Gamma-Ray Activity". Proc Czechoslovah 8t . k Spectroscopic Conference, Ceske Budejovice, June 19-24. (abstract). S.Lend . (1983)aA . "Modellin Terrestriaf go l Gamma-Ray Fields" Polish)n (i , , Sei. Bull, of the Academy of Mining and Metallurgy. No. 966, Serial Mat-Phys-Chem. Bull. 62. 9.Makhabane J.L.(1991 determinatioh )As neutroy nb n activation analysis. Archivef so Mining Science (401-416)6 s3 . 10.Palka K.W. (1983) Proceeding of the Symposium on Methodological Problems in Mineral Resource Investigation Using Borehole Logging Techniques. Inst.Geophysics, Universit Mininf o y Metallurgyd gan , Krakow, Poland 105-11p p , Polish)n 4(i . 1 l.Winegartner E.C.,Rhodes B.T. (1975). An empirical study of the relation of chemical propertie fusioh as no st temperatures. Jour Engineerinf o , Powerr gfo , Trans. ASME, 395-400.

108 APPLICATIO X-RAF NO Y BACKSCATTERING TECHNIQUES ON TURKISH COAL ANALYSIS

. ARKANP . ZARARSIZA , . KIRMAZR , E EF . N , Turkish Atomic Energy Authority, Ankara Nuclear Research and Training Center, Ankara, Turkey

Abstract

X-ray fluorescence method using backscattering for the determination of ash in domestic coals were studied in their as- received forms. Fluorescent intensities from major contenf o t minera singl, l Fe d thei matte, an y Ti r , rcombination Ca suc s a h s were employe conjunction i d n wite reciprocath h e backscatth f o l - tering intensity in a empirical relationship- The results of the analysi. % varo t 0 4 ye o sar frot 6 m

Similar equations r sulphufo , d calorifian r c valuef o s domestic coal were developed in the basis of the Compton and Rayleigh intensités originate from the all scattering properties of coal elements. Sulphur contents are about between 1.2-4.5 % and calorific value samf so e sample foune sar d 35OO-51OO Kcal/Kg.

The relationship betwee e scatterinth n f X—rayo g s from coal samples and their ash, mineral matter were presented in terms of linear and second order polynomial functions for samples methoe Th employes . wa comprisind% 5 asseso 2 t d o froh t sas g6 m the Rayleig d Comptoan h n intensitie f 22-2o sV X-ray a ke 5 s a s means of providing material specification not obtainable with conventional methods.

1. INTRODUCTION

Turkey has large resources of coal mostly lignite reserve. Under the management of Turkish Coal Enterprises (TKI) there are 12 subsidiary establisments producing coal and marketing.Coal produced is consumed in three sectors, thermopower stations, industry house hold and commercial heatings. Thermopower sta- tions consume over 75 % of coal produced by TKI.

109 The total coal production increase n estimatea o t d O 5 d million tons during 1993. Low quality domestic coal yields large amounts ash and sulphur making it less desirable for applica- tions.

In coal industry non-nuclear methods are being used which s havini g highly time consuming conventional procedure. Thers i e a considerable demand for a rapid and sensitive method of moni- torin t onl gn no coai y coa h l as lindustr t alsr powebu yfo o r statio steed nan l industry.

e requirementth f o e Turkise On th thas si f o th Coal Enter- prises and concern analysis technique of ash in coal has rapid analysis time, adequate sensivity, simple sample preparation.The technique describe n thii d s wors developewa k d primaril o meet y t these requirements.

The idea of applying XRF technique to analysis of the ash conten t new no f coa o t. s A i widl e rang f nucleao e r techniques have been carried out in details during the last decades for studies of coal in this way [1-6].

The application f nucleao s r technique n explorationi s , mining and coal preparation, in particular, have been reviewed by Clayton [7]. An XRF technique involving a 3O mCi Pu-238 as a o channetw sourca ld thian e n Nal(Tl) crystal spectrometes wa r develope analysie th r fo d coaf s h o sample las y Narayansb . al t ae d co-workeran [8]o Ra .] applie [9 s d fundamental paramete- ap r analysie proacth EDXRFSy r b fo hf coaso h as l. Renaul s trieha t d to develop a relatively simple XRF method for determination of New-Mexicn i h as o coals usinr tubC ea g [1O]. Dziunikowskd an i Stochalski have determine h contenas e y measurinb tth dF XR e th g of some minerals with a diffraction spectrometer [11].

Dale and Matulis have demonstrated that the ratio of the Rayleigh(coherent) to Compton(incoherent) intensity is a suitable measure of the mineral matter in coal [12].

110 In proposed paper the determination of ash, sulphur con- tencalorifid tan c valu f Turkiso e h coa meany b l f X-raso y back- scattering method, have been studie n detailsi d h monitoAs . r syste ms constructe wa usin F XR g r testinfo d g some domestic coal samples. Besides that e relationshith , p betwee e scattereth n - X- d rays from coal sample d theian s r ash, mineral matter have been presented in terms of linear and second order polynomial func- tions.

. X-RA2 Y BACKSCATTERING METHOD

Impingent X-ray e scatterear s e sample y atomth b d f o s, both coherently (Rayleigh d incoherentl)an y (Compton). Incoher- ently scattered X-ray photons suffe n energa r y loss which grows angle large th f scatte o es a r r increases while coherently scat- tered photons have the same energy as the primary photons regard- les f scatterino s g angle e probabilitTh . f scatterino y e th n i g medium inte elementath o l solie directioth d n i angl , 0 o nd e e dependdifferentiath n o s l scattering cross e sectioth r fo n scatterin e atomith g d e substancecangl an th numbe a f ç eo Z r .

The cross-sectio a fre f eno electro r incoherenfo n t scat- tering in a direction 0 is given by the well-known Klein-Nishina equation

da l E' r E E' (——) n2 f—— - —— - sin20 l (1)

J d Qp 2» F L P E e classica th wher= Z.SxlO"* s _ i r e lm c _ electro3 n radiusl Al . Q definition of symbols is given in Table 1.

The differential cross—section for Compton scattering is r l , , -i~a2 (l-cos0)2a rd , - 2 2 2 —-—=—— re l+a(l-cos0) l+cos 0+ —————————— S(X,Z) (2) L J l+a(l-cos0 L J ) 2 dQ

111 differentiae Th l cross-sectio Rayleigr nfo h scatterins i g

r 2 (H-cos20)[F(X,Z)] 2 (3) do 2e

S(X,Z) incoherent scattering functio d F(X,Zan n ) atomic form factor values have been calculated theoretically, generally based on the Hartree-Fock or the Thomas-Fermi models of electron distributions and tabulated by Hubbell et al.[13]_

The expressio r primarfo n y fluorescence intensite b n ca y used to calculate scattered intensity [14]. Consider an infinite- ly thick specimen intensite ,th incoherene th f o y t (Compton) peak is

_ ro Kl ginc

Similarly, the intensity of the coherent (Rayleigh) peak is

co.^— nt-

A US(E)

K2 is a constant slightly different from Kj^.

The Rayleigh-to-Compton ratio (R/C) is then given by

\ f£ _ • =• >- ' K ~ » ï ' . _ T n co n R2 ^ J.^^.K c l K line

It is evident, R/C can be simplified by ns(E)« MS(E*) approximation. Furthermore, the R/C is independent of mass ab- sorption coefficients whil intensite eth scatteree th f yo d radia- tion and the intensity of the fluorescent radiation are a measure mase th s f absorptioo n coefficien composita f o t e matrix.

112 At this point, coal may be considered as a two-component mixture consisting of organic fuel substance (low Z medium) and incombustible mineral matter (high Z materials). The composition of minerals is a useful guide to the ash content of the coal. The physical technique of radioisotope X-ray backscatter for measur- men f tota o th includeas l s compensatio o reduct n e o errort e du s variations in ash composition. The incoherently backscattered X- ray decreases with increasing ash content in coal with inverse relation totae conten.h Th las s computetwa followiny b d g regres- sion equation [15].

B Ash(%) (7 )—————= CE il—+ i -tD - ) (i=CaFe , ,Ti

where coefficientse th e ar D , B.,C^ Ij is the fluorescent intensity from the i-element (Fe,Ca,...). 1^ is the intensity of incoherently backscattered beam

B, Cj, D were obtained by multiple linear regression that e techniquth s i f least-squareo e s fitting whic e havw h e develop fall unde generae th r l nam f regressioo e n analysis. Calculations were made after including in the equation characteristic intensi- ties from elements taken singly or various combinations.

Following equation illustrates empirical relationship between ash content, coherent and incoherent backscattered peak intensity writtee same b th n e n ca i forn t Eq.(7f .I o m )

B ) (8 CE i l+ i+ Ash(% A-I— D —— + r )=

where

A,B,Cj, coefficiens i D t

Ir is coherently backscattered intensity.

113 Modified Eq.(7) was proposed for ash monitor

8 Ash(%) = ——— + C-I__"anororag -I- D (9) It

where

B,C,e coefficientar D s

s backscatterei t I d peak intensity

Ianorg is peak intensity of anorganic elements

All coefficient e obtainear s y multiplb d e regression analysis method using coal specimens of known ash content

ANALYSIH AS . 3 S [16]

e experimentTh s were performed using energy dispersiv— X e ray spectromete t Ankara r a Nuclear Researc d Traininan h g Center. A selectio f welo n l characterized Turkish coals were use o test d t the method. About fifty coal samples from different mines were obtained from Turkish Coal Enterprises.

Each sampl s powderewa e o -1Ot d O mesh sizd briquettean e d under 1O T pressure. A technique which has been adopted with succes s basei s n takino d g three separate sub-samples from each of coal S referencsampleNB d an s e materia f coal.Tho l e amounf o t the samples was taken at saturation level that the intensities of each scattere peaF df XR minerao k pea d an k l matter were independ- enf amouno t f materialo t .

The most important consideration in using the backscatter- inf X-rayo g n thii s s applicatio e choicth f s incideno i en t radiation energ d thi an s y governei e svariation th e y b th d n i s compositio d concentratioan n f minerao n l e coalmattee th Th .n i r mineral matte f eaco r h coal sampl s determinewa e analysiF XR y b d s using Pu-238 whic s X-rayha h s wit K absorptio he E>7.1(F V ke n1 edge).

114 Fig.1 illustrates domestic coal spectru y Pu-23b m 8 excita- tion source s X-raIt . y line e slightlar s y abov e absorptioth e n edge of mineral elements. The schematic diagram of the experimen- tal setup used in all experiments is shown in Fig.2.

n e annulasystea Th s ha mr symmetry aroun e verticath d l axis. Canberra Si(Li) detector having the resolution of 21O eV at s user detectionwa fo dV ke s activ9 It .5. e0 mm 8 aree 2s .Th i a detecto s connectewa r d with high quality commercia electronM NI l - ics, 8192 channel analyzeM computer.ThIB d an r e known reference materials and unknown coal samples were analyzed with instrumen- tal parameters set identical to above mentioned setup and meas- ured backscattering and fluorescent intensities of Ca.Ti.Fe simultaneously.

e see b e calculateTabln i nn th I ca t2 e d value f B,Co s ^ and D coefficients for single or various combinations of elements and the corresponding R - square values were determined. The ash content for each coal sample was obtained using experimental 1^ anvaluej I d calculated D constants an s, j C , B d .

The results of ash content in lignite samples were summa- rize n Tabl i Geometrica. d 3 e - h contende as ls e a tshapth f o e fine n Eq.(7i d r Comptofo ) n scattering with mineral element intensity is given Fig.3.

. SULPHU4 R CONTEN CALORIFID AN T C VALU F COAO E L [17]

Similar sample preparatio s appliewa n d experimentaan d l setup was used for measurement of sulphur and calorific value of domestic coals.

Sulphur is compounded with mineral in mined coal mostly iron whic s dominani h t elemen f asho t . Sulphur conten n domesi t - tic coas determinewa l y usinb d g standard comparison including backscattering metho y Eq.(7).Regressiob d n coefficientr fo s

115 sulphur expression are given in Table 4. Results of analysis are illustrated in Table 5.

This technique can be employed for the measurement of calorific valu f coao e l using similar consideration inversly with Eq.(7). Calculated regression coefficients for calorific value are given in Table 6 by using NBS reference materials. Calorific values of domestic coal samples are summarized in Table 7.

MONITOH AS . 5 R

Ash monitor system using X-ray fluorescenc s designewa e d for testing some coal sample n laboratoryi s . Cd-lO9 radioisotope source » Nal detector , portable MCA and necessary NIM modules are the component of the monitor system (Fig.4). Spectrum of X- ray fluorescenc f minerao e l element d backscatterean s d x-rayf o s coal sample, whic s obtainei h d with monitoras h s illustratei , d in Fig.5.Regression coefficient values are given in Table 8 according to Eq.(9).Ash content in domestic coal , measured by ash monito e summarizear r Tabln i d . 9 e

RAYLEIG, H AS . COMPTO/ H6 MINERA, N L MATTER RELATIONSHIP [18]

The scattered radiation generally regarded as a nuisance due to contribution to background intensity. However , the method of using Compton scattering intensity has been employed for correctio f absorptioo n enhancemen- n t effec somn i t e cases.Since the strong dependence of the Compton intensity on the matrix mass attenuation coefficient and chemical composition of the samples beeha nt i ,use o determin t dh conten as e f coalsth o te . This metho s receiveha d d increasing attentio n receni n t years which allow f iroo n coalsF i n XR treatmen .e th r fo t

The fundamental reason for using scattering intensities in addition the fluorescence X-rays emitted by samples are to obtain information on the sample composition furthermore is

116 relate o determint d e heavy element n lighI s t matrix. Besides that, the suitability of Rayleigh / Compton intensity ratio to ash of coal which is normally taken to be equivalent to the mineral matter were depicted with functions.

The coal sample Table wer) se 9 e( se irradiate monoa d - energetic X-ray source which is emitting 22 - 25 keV X-rays.The measurements of characteristic X-rays following K-shell ioniza- tion and backscattered X-rays were carried out with measurement component that describe e spectrometen Sectioi Th d . 3 n s i r optimize r resolutiofo d d energan n y calibrationf o e us e Th . method has facilitated the study of the relationship between coherent and incoherent scattered radiation and chemical composi- tio leadin, nevaluatioe th h conteno t gas f h o nf coals o as t e .Th conten n coai t l samples from different mine s foun wa so var t d y between 6 and 25 %.The results , which are shown in Table 1O , indicate relationship between scattered X-rays and compositional dat f coao a l presente n lineai d r quadratic forms.

The use of different relationship gives varying degrees of fits [see Figs.6-9].The equations have permitted detailed exami- nation of the factors influencing the method.

. CONCLUSION7 S

The X-ray backseattering method using some assumptions and expression s beeha s n applie o determinatiot d h percenas f o n t , sulphur conten calorifid an t c valu f Turkiso e h coals.

About seventy domestic coal samples were analyzey b d proposed method and the results show that ash content varies from 6 to 40 % in samples-Sulphur contents are about between 1.2-4.5 % and calorific value f samo s e sample e founar s d 3500-51OO Kcal/Kg. All results were obtained by experimental IL.., I_, ZI^ values and calculated A,B,Cj[,D values by multiple linear regression method.Incoheren d coherenan t t backscattering were employed

117 singly and totaly. The agreement between XRF and Turkish Coal Enterprises result fairls si casesl yal goor .fo d

improvemena e resul th s A f to experimentn i t s mentioned above h monitoas , s designewa r n ordei d o test r t some domestic samples in laboratory.Analysis of these samples gave results which were in excellent agreement with the expected values and verified the suitability of this calibration procedure for deter- mining of qualification of coal .The calibration demonstrates the validit f thio y s procedur sampler fo e f varyinso g mineral matter, mostly iron content, becaus essens i e e compensatioF - f o F XR r fo n tial for estimation of the ash fraction.

Disadvantage of method is limited particle size accept- f higheo e rus ancenergiet ebu r finso e grindin f samplo g e over- come this trouble.Work along ash monitor on field is in progress.

Tabl Definitio. e1 symbolf no s

E, initial photoe energth f nyo scatteree energ, th E' f o y d photon , scatterin0 g angle 2 a, E/m0c

electro, 0 m n mass c, speed of light S(X,Z), incoherent scattering factor Z, Atomic scatteree numbeth f o r r

X, sin(0/2)/A ^, initial wavelengt e phototh f nho F(X,Z), atomic structure factor K^, proportionality constant for incoherent equation

IQ, intensity of the incident radiation ainmas ' c s incoherent scattering coefficient

Ms, mass absorption coefficient of specimen A, geometrical factor l<2, proportionality constant for coherent equation °co mas» h s coherent scattering coefficient

118 Table 2. Calculated values of B,C.,D and R for various combination elementf o s

2 i UX1ru-i Un ^ • ... -. * D R Ca Ti Fe Sr

Ca.Ti.Fe 1.418 -4.785.10^ -«<.907.10~5 -8.111.10~ - 11-0.43 H 0.998

Ca.Ti 1.167 8.422.10"6 -it.SSS.lO"'' -1.929 0.998

Ca.Fe 1.058 1.765.10"1* 2.185.10"5 - -3-157 0.997

Ti.Fe - 1.17-4.936.10~6 6 -1.591.10~6 - -1.847 0.997

Ti 1.167 - -4.314.10"^ -2.881 0.994

Fe 1.138 -6.197.10~ - -1.965 8 0.992

Ca 1.171 -6.591.10~5 -2.784 0.994

Fe.Sr 6.926 4.588.10~1*''2.856.10~1' -10.22 0.982

Fe 7.744 1.954.10^ - -8.505 0.982

Table 3 . Results of ash conten t lignitn i e samples

XRF TCE Coal fields in Turkey Coal mines calculated % ash reported % ash (average values) (limit values)

Önen I 14.98 Soma 15.32 e Eg ÖneI nI 20.10 12-42 Denis 22.58 Darkale 40.24

Alpagut I 11.50 AlpaguI I t 17.74 Alpagut-Dodurga AyvaköyI 23.34 12-35 Dodurga 27.41 Ayvaköy II 35.24

Seyitömer I 23.07 Tunçbilek I 31.32 TunçbileI kI 32.59 Garp 18-45 TunçbileI kII 34.03 SeyitömeI I r 37.35 Dumansiz yakit 23.90

119 Tabl . (cont.3 e )

XRF TCE Coal fields in Turkey Coal mines calculated % ash reported % ash (average values) (limit \alues)

Can I 7.86 Can II 9.83 Keles 10.04 Marmara Orhaneli 10.22 10-30 Can III 11.53 Saray I 25.11 Saray II 26.13

Ilgm 11.46 Konya Ermenek 19.20 11-35 Beysehir 32.83

Silopi 1 2746 §irnak I 2944 Guneydogu Anadolu 20-15 Silopi II 31 60 Sirnak II 38.01

Yatagan 16.69 Sekkoy I 25.09 Guney Ege Sekkoy II 27.00 15-29 SekkoI yII 27.95 Bagyaka 28.11 Tmaz 29.15

OIiu Sutkans I 12.92 Kukurtlu 2081 Ispir 21.86 Dogu 10-30 Karhova 24.24 Oltu Sutkans II 25.23 Oltu Balkaya 26.02

Ki^lakoy I 22.02 Ahin-KIbibtan 13-2U Ki^lako1 1 y 21 65

Bolu Goynuk 12.55 10-15

Çayirhan I 26.94 Orta Anadolu 20-28 Çayirhan II 28.04

Sivas-Kanga! Kalburçayi 1971 15-30 «

120 Table 4 . Regression coefficients for sulphur

6 5 2 i B x 1O C± x 10~ D R

Fe 8.3 4 4. 1—4.4 8 0.99

Tabl Result. e5 sulphuf so r analysis

Sample % , S S-6 , o/ (XRF) (TKI)

KLI 4.2 4.0 ELI 1.2 1.2 OAL 4.8 4.8 ADL 1.8 1.8 DLI 3.2 3.2 MLI 2.4 2.4

Table 6 . Regression coefficients for calorific value

B x 1010 Cj X 1O~2 D x 1O3 R2

Fe -1.48 2.O2 13.78 O.99

121 Tabl Calorifi. e7 c value domestif so c coal

Sample Calorific value Calorific value Kcal/Kg, (XRF) Kcal/K (TKI, g )

KLI 4100 400O ELI 4950 49OO OAL 36OO 35OO AOL 35OO 35OO DLI 5100 515O MLI 475O 475O

Table 8 - Regression coefficients for ash monitor

10~x C 5 7 1O x 8

2.06 9.6O 8.89 0.99

Table 9. Result of ash contenn i t domestic coal samples

Coal fields Coal XRF E TC Ash monitor in Turkey mines Calculateh as d% Calculated % ash Reported % ash (average values) (average values) (limit values)

Soma 6.3 6.2 K.dere I 9.4 9.0 Ege K.dere II 6.4 6.5 9-25 Deniç I 20.6 2O. 5 Denis II 20. 7 19.2

Yatagan 1O.5 1O.4 Güney Ege Tinaz 11.2 11.4 10 - 25 Bagyaka 15.2 14. O

Orta Göynük 15.8 8 2 - 5 1 16.8 Anadolu Cayirhan 25.3 25. 0

S . öme r I 8.O 8.4 Garp S. ömeI I r 12.0 11.8 5-15 Merkez 12.3 12.2

Afsin- Elbistan 15.2 14.5 5-20 Elbistan

Alpagut- Merkez 7.5 8.5 5-20 Oodurga

Konya Ilgin 8.9 8.2 5-20

Marmara Can 17.2 17.1 10-30

122 Table 10. The relationships between Rayleigh (R) and d mineraComptoan ) (C ln matter (MM d ashan ) .

Relation Fitted curve Correlation Coefficient

MM - R/C quadratic O.992 C R/ As - h linear 0.980 Ash - MM quadratic 0.991 Ash - 1/C li nea r 0.993

TIME (L) = 5000 CRT = (01% 0 -04 = T )D 1 1. UNI . TNo 500= PSE ) 0(L T TAG NO. = 0 1023 CH No. 819= OCHNo S 2VF . CANBERRA c o t-> Q. £ o u

c o \J

c a»

300 600 900 Channel number

e spectruFigurTh . 1 ef domesti o m c coa y Pu-23b l 8 source.

123 ) Sample

Pu Source Collimator

Multichannel analyser

IBM XT

Plotter Printer

Figur . 2 eElectroni c block diagra f setuo m p

ASH(%)

38S5 219428 9795 340280 20164 551718

Figur . 3 eRepresentatio e geometricath f no le shapth f o e h contenas r Comptofo t n scattering with mineral elements intensity.

124 ?reamp.

r sampl\— N e holde

monitoh FigurAs . r4 e

15K

_ta Scattering region

10*

Anorganic

,-v'v

512 Channel number

Figure 5. Coal spectrum by ash monitor

125 Mineral matter (xlO)

Figure 6. Relationship between R / C and mineral matter for coal samples.

91 r-

o

o ex 51 —

i i i l i/ i i l i i i i l i i_ i i l i i i i 1.1 i < i J 0 3 5 2 0 2 5 1 0 1 5 0 Ash (%)

Figure 7. The ash content in coal plotted against R / C.

126 150

120

o 90 ^

Vvl ~ g 60

30 -

i l i i i i l i i i i l i i i i l 0 3 5 2 0 2 3 1 0 1 5 0 Ash (t)

Figur . 8 eRelationshi p betwee coan minerad i an lh nas l matter.

0.57

0.53

0.49

0.45

0.41

0.37 i i i i l i/i i i l i i i i i i i i i l i i i i l i i i f I 0 3 5 2 0 2 5 1 0 1 5 0 Ash (X)

Figure 9. Measured 1 / C by the ash content

127 REFERENCES

1. Rhodes J.R.,Daglish J.C. and Clayton G.G. Radioisotope Instruments in Industry and Geophysics I (1966) 457.

2. Radioisotope XRF Spectrometry Technical Report Séries No.115, IAEA, Vienna (197O).

. Brow3 n F.VJoned an . s S.A. Advance X-ran i s y Analysi 3 (198O2 , s. )57

4. Auermann R., Russ J.C. and Shen R.B. Advance X-ran i s y Analysi 3 (198O2 , s. )65

5. Pandey H.D.,Haque R. and Ramaswamy V. Advance X-ran i s y Analysi 4 (19812 , s ) 323.

. Schlorholt6 Bombad an . . M yzS Advances in X-ray Analysis , 27 (1984) 497.

7. Clayton C.G. Applications of Nuclear Techniques in coal industry. Proc. Int. Symp. Nucl. Tech. Min. Resources IAEA - SM - 216 / 101 Vienna - Austria (1977)

. , Umamakeswaral . Narayan S. 8 t e . G , . K. aD o Ra a X-ray Spectrometr ) (1986(3 5 )1 191, y .

. Venkateswar9 Raghavaia, N. o Ra a . h al C.V. t e , X-ray Spectrometr ) (1987(3 6 )1 147, y .

. Renaul10 . J t Advance X-ran si y Analysi 3 (19802 , s. )45

. Dziunikowsk11 d Stochalskan B i iA X-ray Spectrometr ) (1984(4 3 )1 , 151y .

128 12. Dale L.S and Matulis C.E X-ray Spectrometr 6 (19871 , y ) 113.

13. Hubbell J.H.,Veigell W.J. , et al. J. Phys. Chem. Ret. Dat(19754 , a ) 471.

14. Tertian R and Claisse F. Principle f Quantitativso AnalysiF eXR s (Heyden & Son Ltd. London ) 1982.

Shastrd . Pandean 15 D yH. y C.R. X-ray Spectrometry 11(4) (1982) 154.

16. Arikan P., Zararsiz A.,Efe N and Turhan S. International Symposiu f Nucleao m r Technique e explorth n si a tion and exploitation of energy and mineral resources Jun8 5- e 199 3 0 0/ Vienn8 3O - a M IAES Austri - A a

. . ArikaN 17 e , ZararsiEf P. n d an zA Nuclear Geophysics , last issue (1993)

. Arika18 n P.,Zararsi. N e Ef , Kirma d zA. an R z Nuclear Instrument Methodsd san , publishede 199b o 4(t )

129 APPLICATIO NUCLEAF NO R TECHNIQUES FOR ANALYSIS OF VIETNAMESE COAL AND EMBEDDING ROCKS

BANGC VODA , PHA DUONGN MVA , NGUYEN THANH BINH TIEE L , N QUAN, NGUYEN MANH HUNG, NGUYE I HONGNTH , VU HOANG LAM Institut f Nucleaeo r Technology, Departmen f Nucleao t r Tecniques Applicatio Industryn i , Viet Nam National Atomic Energy Commission, Hanoi, Viet Nam

Abstract In the paper the result of elemental analysis by Nuclear Techniques of Coal and Embedded rocks samples from Vietnamese Quang Ninh and Thai Nguyen basins were presented. Methods used were: Neutron activation Analysis at Dalat Reactor, low counting with HP-Ge and NaJ detectors and X-ray fluorescent analysis with planar Si (Si) detector. Mean concentrations of 19 elementn rocki 9 s n coa d i swer an l e determined. Correlation between concentration f elemento s s were found t appearT . s that the correlation concentration, betweeTh , constanh K nas , U d tan s was poor for Quang Ninh antracitecoal. Correlation coefficient was found to be 0,63 for ash range 0-40%. Content of Th in anthracite Quang Ninh coal was much higher than reported in literatur r subbituminousfo e , bituminou d lignitan s e coals, while Thai Nguye coat fa nl contains considerable , amounCu f o t . ObtaineZn , Pb d data were usefu r evaluatiofo l f potentiao n l hazard for environment from using coal as fuel for coal fired power plants r estimatiofo , f possibilito n f usino y g nuclear technique in coal industry in Vietnam. They could be used also for geochemical investigations. The simple of-line coal ash gauge basin attenuation go soff no t gamma radiation from Fe-5 alss 5wa o described.

INTRODUCTION Recentl n coai y l exploratio d exploitatioan n n more attention is draw up to the aspects of potential hazard for environment by using coal as a fuel for coal fired power plants and, on other hand, the possibility of using coal natural radio- activit costw lo ,r fo non-radioactivy e sourc h gaugas e e [1]p ,U e correlationth w tno o s between natural radioactivith as d an y content were published for subbituminous, bituminous and lignite coals [1]. There wer o investigationn e r anthracitfo s e coal. Earlier, since 1950's the fact that coal low level of natural radioactivity in comparision with embedded rocks have been used to identify coal seam d measurean s s their thicknesses [2]. Variatio chemican ni l compositionn i , Mn , , especiallTi , Ca , yFe coal ash also influence strongly on precision of coal ash gauge based on the principle of gamma ray attenuation. In Vietnam, total estimated reserved of late Triassic coal is 6,600 millions tons. Among them 6,500.' million tons of coal belong to the Quang Ninh basin, where the coal industry has been developed. The coal production of Vietnam for period between 1955 to 1990 is more than 136 million tons. From 1989 in Vietnam

131 the coal production becam decreaso t e e fromillio5 6, m n tonn (i s 1988) to 3,5 million (in 1990). But , as an important branc Nationaf ho l Economics coae ,th l industr estimates yi o t d increase its production to the value of 9,5-10 million tons in 2000 year. Development and applications of the nnclear techniques in the coal industry is one of the ways to improve the quality of coa suppord lan productioe tth n raise Vietnan .I m since 1980s this investigation of nuclear gauge in the coal industry has been carried out [3,4]. In this wore contenth k f traco t e elementn i s Vietnamese raw anthracite coal and embedded rocks were determined by nuclear analytical techniques, conclusions were madn o e possibility of using natural radioactivity ash gauge, potential impact on environment from using coal as a fuel could be estimated from coal elemental composition determined. e Thfirsth e twors e wa nucleaattempkus o t rt techniques for multielemental coal and embedded rocks analysis n Vietnam i e resultth e somewhao s ,ar s t modest. Undoubtfully, much larger programme should be formed for full scale investigatio e problemth f o n .

EXPERIMENTAL 57 samples of coal and 18 samples of rocks (Sandstone, Aleurolite, Argillite) from Thai Nguyen and Quang Ninh basins were collected. Each sample weighting 300-500 g were grinded to the grain size d fine0.0 fluorescenr an fo 2rm m t analysis. , Co , Ni , Hg , Se , r determinatioNAAs fo A, Zn , Cu f o n Th, U contents were carried out in the Dalat nuclear reactor analyticae .Th l procedur followins ewa girradiatio: n i n dry channel with neutron flux 2xl0lz n. cm'1 s with standard samples, cooling tim 7-1s ewa 5 days, measurements were made with gamma spectrometry system consisting HP-Ge 70 cm3 coaxial detector couple multichanneo t d l analyzer Canberr d PC/Aan T0 4 a computer. For determination of Hg, Se, Cu, was used radiochemical separatio extractiot we y nb Dimethyn ni l dithyo carbonatd an b eP dithyso d combustean n d method describe n [5]i d . Som f gammo e a spectrogramme Standard. 1 g sshowe fi obtaine ar n nA i s NA wer y db e prepared from high purity graphite powder as matrix and addition of certain quantity of Zn, Cu, Ni, Cd, Hg, U, Th in solution. By ppm0 3 thid . an s Lowe 0 conten1 , r3 conten, I t f elementto s were determined by method linear expansion. For checking of analytical procedure IAEA standard sample SRM-1633A was analyzed. In table 1 the result of analysis of SRM-1633 was presented.

countinw Lo g techniques including detecto 3 Hp-Gcm 0 e7 d ran BICRO crystalJ NNa l couple CABERRA-4o dt 0 multichannel analyzer were used for natural radioactivity mesurement. HP-Ge detector has sensitive volume 66 cm3 and resolusion l,77Kev at 1,33 Mev. Obtained data were proccesse y EMCAPLUb d S fitting programmf o e SILENA company. m c 7 7x l Na s carriey b wa Determinatiot K ou d, Th , U f o n detecto channe4 d an r l analyzer with convertional procedurf o e e solvinsyste3 equationth f f o o m g r eliminatinfo s e th g interplay between these elements. Detection limits for U, Th

132 determination for measurement at Dalat reactor by activation analysis were 0.01 ppm, for low counting device, with Hp-Ge 4 hou(2 r m measurementpp detecto1 0. dévidj Na s r wa e ) fo were 0.5 ppm (U), 0.1 ppm (Th) and 0.08% (K). To avoid non-equilibrium effect l sampleal s s measured were 0 day3 seale sr fo beford e measurement. Gama-Spectrogrammes of natural radioactivity obtaine Hp-Gy b d e detector were pictur e showth n . ni 2 e 21 samples were analyze y X-rayb d ' fluorescent device including Si (Li) planar detector with resolution 160 ev at 5,9 key. Electronic blocks (preamplifier, amplifier, HV supply and multichanne C baseP l d analyze rwer) e suppliedby SILENA company. Each sample weighted 10-2 Excitatio. 0mg n source-Cd-109, 30mCi. Measuremen te sample timon hour3 r - e. fo s Standers used were combination of NBS River Sediment, Orchard leaves, bovine liver, milk powder, dried blood. Measured data were processed by X-ray fluorescent analysing programme AXIL. X-ray spectrogram is shown in the picture 3.

RESULTS AND DISCUSSIONS. The content radioactivn no f so e trace element associaten si d rock sample d coa an sQuanf lo g Nin Thad han i Nguyen basins were shown in the table 2,3. The concentration of heavy metals (Pb, Hg, Cd) for rocks only a little higher than in Quang Ninh coal. At the same time Thai Nguyen fat coal is very rich by Cu, Pb, Zn time0 2 b P s d highean u r(C tha coal)N nQ . Variation in silicate components of Thai Nguyen and Quang Ninh coal are shown in the table 4,5,6. The variation ranges of

FeO, CaO, O tha Mn Tiot influence strongly coah gaugeas l s 3 / 2

basin2 n attenuatioo g n principle were much wide n Quani r g Ninh coal basin than in the Thai Nguyen one. It can be concluded that such gauge shoul e morb d e favourabl r workine Thafo eth i n i g Nguyen basin. A special method should be applied for these type gaugeh oas f s working with Quang Nin lashe coalth t n parI .f to this paper the method will be reported for of-line ash gauges capable to overcome in large scale this difficulty. Among now available on conveyor ash gauges it seems more suitable for the Quang Ninh coal pair-production type [6]. The result naturae th f so l radioactivity investigations were presented in the table 7 for embedded rocks and coal. The cocentration of U, Th, K for rocks from Thai Nguyen basin did not differ significantly from Quang Ninh data whilt conten.e Bu eth t K wer e samr botd th efo an e h oU fbasins , concentratiof o n thoriu Quanr fo m g Ninh Basi s mucnwa h higher contente .Th U f so and Th, K and Th showed no any significant correlation between them fairle .Th y good correlatio s establishenwa d an d U onlr fo y 0,1> U 5d e rangan ppm th 700< t onlm bu n K e.0pp i y K Another correlatio betwees nwa contenh nas concentrationd tan , Th , U f so K described by equation % ASH = AK + BU + CTh + D. The iteration programme was created for determination of this correlation. Correlation coefficient was found to be rather low. In the table 8 where shown correlation coefficients between content of several elements and ash. Significant correlation was observed only widn i e Y betwee d contenrang, an Sr Ashf h o ef nas o t .

133 Coal samples analyzed for estimation of the correlations between ash and content of natural radioactivity were collected from three mine of Quang Ninh Basin. They are raw commercial coal samples conserved in mine's storeys. So they coul e frob d m different seam d obtainean s d results coule b d considere facs da t that different mine Quann si g Ninh Basin have "unrelated" seam speciad san l investigation shoul carriee db t dou for every mine and may be for every coal lenses. Another possibility was the weak relationship between natural radioactivit anthracitr fo h as d e an ycoa l that hav t beeeno p nu to now investigated yet. CONCLUSIONS Determinatio f elementao n l compositio f Vietnameso n e anthracite coa t d embedde,fa an l d rock beed sha n carriey b t ou d nuclear analytical techniques. Concentrations of up to 26 element n coad i srock an l s were investigated. These data could be usefu evaluatior lfo potentiaf no l hazar usinf o d g a coa s la fuer coafo ll fired power r constructioplantfo d coah an sas l n material fabrication. They also coul usefue b d r geochemicafo l l investigation s observewa , t Zn I . , d As tha e conten, th tCu f o t Than i Pb ie , S Nguye n embedded rocks were much highe factoy b ( r r of 4-13 ) than in Quang Ninh ones. Among them such poisonous elements as Pb and As were higher by a factor of 8 and 13. In werB coalTN e n ,highei concentration Z r, B thaPb QN n , ni Cu f no by a factor of 28,24 and 4 correspondingly. Investigation of the natural radioactive elements concentratio anthracitw ra B QN n ni e coa shows lha n that thers ewa weak correlation between their concentratio valuesh as d e n.an Th reason for this phenomenon was explained either by "unrelated" QNB coal seams or by special geological process of the anthracite coal basin formation. In any case, undoubtfully the further more detailed investigations were neede r fulfo dl resolutioe th f o n problem. A simple ash gauge that had weak dependence on iron content variatio s constructewa coan h i ne firs las th ts a dste p toward nucleonie sth c control systems applicatio Vietnamesn ni e coal industry.

TABLE 1. THE RESULT OF ANALYSIS OF SRM-1633 SAMPLE (Concentration PPmn si )

Method AS Cd Cu Hg Ni Pb Se Zn U Th

Certified 145 1.0 118 0.16 127 72.4 10.3 220 0.2 24,7 values N A A 130 1.10 128 0.10 136 9.0 210 0.25 23.1 AAS 110 0.19 77.5 231 Polarography 129 0.20 63.1 228 countinw Lo g — — — — — — — — 12.1 21.3

134 Table2 CONTENE TH TRACF TO E ELEMENT EMBEDDEN SI D ROCK SAMPLES OF QUANGNINH AND THAINGUYEN COAL BASINS (Determine) Pb y INAAr b d fo elementl ,S al AA RNA r d fo Aan s

Mine Sample Namf eo Content, PPm Index Sample Cu As Zn Co Ni Cd Pb Se Hg

Khechuoi 9215Q Sandstone 187 18 63 3.0 10 0.8 90 7.3 0.3 9216Q Aleurolite 141 10 70 5.0 8 0.2 85 5.1 0.1

Dongvong 9218Q Sandstone 120 8 55 5.0 10 0.3 35 8.0 0.3 9220Q Sandstone 110 12 64 3.0 - 0.2 20 6.0 0.1 9222Q Sandstone 190 18 80 4.0 10 0.4 40 6.0 0.2

Trangbach 9230Q Sandstone 100 10 40 _ - 0.2 20 4.0 0.2 9231Q Sandstone 70 10 38 2.3 - 0.4 50 2.0 0.06 9233Q Sandstone 130 6 60 - 7 0.1 40 4.3 0.10 9235Q Sandstone 100 0.4 100 10 - - 15 4.0 0.04

Cocsau 9240Q Aleurolite 100 0.2 40 - - 0.2 20 4.0 0.2

Khetam 9243Q Argillite 30 16 20 3.0 10 0.3 19 8.0 0.1 9246Q Argillite 61 12 19 5.0 • ' 10 0.2 20 4.0 0.2 9248Q Argillite 40 10 50 10 - 0.1 30 6.0 0.1 9251Q Aleurolite 190 40 181 20 40 0.4 150 4.0 0.2

AVERAGE CONTENT 112 12.2 62.9 6.0 13.1 0.3 44.5 5.3 0.13

Nui hong 9261 Sandstone 437 143 500 10 - 0.4 360 30 0.10 9264 Sandstone 1270 140 400 10 40 0.4 560 10 0.20

Phanme 9269 Sandstone 190 210 360 20 10 0.4 250 19 0.1 9276 Aleurolite 260 150 290 40 10 0.9 190 20 0.1

AVERAGE CONTENT 539 161 388 20 20 0.5 340 20 0.13 u« U) O\ Table3 VARIATIO NON-RADIOACTIVE TH F NO E ELEMENTAL CONTENT COAF SO L QUANGNINR FO H (QNB THAINGUYED AN ) N (TNB) BASIN , SPPr a

BASIN ELEMENT Cu Pb Zn As Cd Se Cr Ni Hg Ça

X MIMA N- 34,3-111.9 13.0-63.4 40.4-163.3 5.9-37.0 0.1-0.5 2.1-10.2 15.3-84.0 9.6-38.5 0.05-0.3 78.8-1060

QNB MEAN 73.0 34.9 71.1 13.6 0.3 6.15 37.2 21.6 0.13 372.2

NUMBER OF SAMPLES 32 30 32 27 11 11 31 31 11 16

MIN -MAX 1640-2730 730-895 201-425 6.1-7.5 — 2.1-12.0 — 0.06-0.25

TNB MEAN 2085 843 318 6.8 0.7 6.0 17.0 0.14

NUMBER OF SAMPLES 8 8 8 8 8 8 8 8 8

N I S BA ELEMENT Ti Y Zr Nb V Fe Br Rb Sr

X MIMA N- 367.4-1691.8 3.9-16.2 10.2-94.5 1.9-5.1 30.2-148.9 928.9-12750 3.07-26.7 16.8-135.9 10.3-41.6

QNB MEAN 1037.2 9.3 34.4 4.0 74.2 5249.2 69.5 69.5 25.2

NUMBEF RO SAMPLES 21 21 21 21 16 21 21 21 21 Table 4 VERIATION OF SILIKATE-CHEMICAL COMPONENT OF COAL ASH (in the Hongai structural range)

COMPO G E O B L O C IC -NENT DONC -TRIEU . MAO - KHE . ^nE N- LAP . HO NGA- 1 CAM- FA.

SiO: 40.51 - 62.31 34.76-68.10. 53.70 - 60.00 37.76 - 61.56 24.02 - 77.72 57.39 54A7 57.06 51.61 46.07

A1A 15.61 -31.25 11.54-36.05 22.6 629.7- 8 17.96-31.49 4.30 - 32.07 26.33 24.99 25.95 22.00 20.39

FeA 1.95-26.13 3.8 43.6- 7 2 1.97 - 8.40 1.48-34.96 4.9 58.3- 7 3 10.64 10.68 6.21 15.68 19.09

C£> 0.18-3'.51 0.27 - -12.40 0.2 - 1.78 2 0.25 - 5.00 0.14- 10.27 0.98 1.93 1.20 1.38 2.32

MgO 0.2 4.3- 5 4 0.61 -5.74 0.78 - 1.43 0.67 - 3.77 0.12-5.06 1.53 1.62 1.06 1.05 2.37

MnO 0.2 0.6- 0 7 0.0 0.4- 1 3 0.15 -0.18 0.0 0.9- 4 9 0.01 -2.16 0.44 0.12 0.16 0.39 0.87

TiO2 0.2 - 1.00 3 0.3 0.9- 0 7 0.0 0.8- 4 7 0.49 - 1.23 0.23 - 1.30 0.78 0.69 0.59 0.79 0.73 u> 00 Table 5 VERIATION OF SILICATE-CHEMICAL COMPONENT OF COAL ASH (in the Baodai structural range)

COMPONENT GEOBLOCK

Hothien Ycnlu Dongvong Average for Baodai Ragion

Si02 25,16-69,71 24,30 - 55,89 31,50-77,84 24,03 - 77,84 57,99 48,56 57,26 48,56

A!2O3 19,31-35,16 8,26-31,45 11,83-39,04 8,24 - 39,04 23,20 20,92 28,02 20,92

FC2Ü3 3,12-47,16 6,83 - 55,76 1,24-44,66 6,8 355,7- 6 13,23 20,50 8,51 20,50

CaO 0,15-0,28 0,3 58,3- 4 0,08-1,62 0,08 - 8,34 0,16 1,49 0,38 1,49

MgO 0,21 -2,13 0,89 - 4,87 0,08-1,94 0,08 - 4,87 0,33 1,43 0,05 0,43

MnO 0,21-1,23 0,00-1,00 0,00 - 0,21 0,00-1,23 0,92 0,43 0,05 0,43

Ti02 0,26-2,91 0,2 33,7- 0 0,20-1,30 0,20 - 3,70 0,77 0,68 0,72 0,68 VARIATIOE TH Table SILICATF 6 N O E COMPONEN THAF COAO N TI I H NGUYELAS N BASIN

HONI NU G. A MINE

Coal lense Si02 A1203 FC2Ü3 CaO MgO MnO TiOz

I 49,91-67,70 14,69 - 23,70 2,79- 10,47 1,61 -12,04 0,48 - 0,85 0,02-0,71 0,15-0,81

60,8) 7(5 19,67(5) 4,29 (5) 4,02 (5) 0,68 (5) 0,25 0,65

II 9,17-72,1 3,94 - 26,50 1,59-54,99 1,39-39,71 0,0 2,83- 4 0,31-0,65 0,21 - 0,73

40,2(19) 12,53(19) ' 17,01 (19) 11,48(19) 1,03 (19) 0,45 0,41

B. PHANMEMINE

1 34,12-45,94 15,50-22,94 22,02-31,99 4,37-10,45 0,92-2,91 0,06-0,30 0,63-0,75

38,70 (3) 18,41 (3) 25,58 (3) 6,7) 6(3 2,02 (3) 0,21 (3) 0,66 (3)

MINIMUM - MAXIMUM

AVERAGE (AMOUN ANALYSISF TO ) Table 7 CONTENE TH NATURAF TO L RADIOACTIVE ELEMENT COA W EMBEDDED RA L AN N SI D ROCKS OF THAINGUYE QUANGNIND NAN H BASINS

of Type of sample m pp , U Th, ppm K ,/) Basin Min - Max x Ma Mi - n Min - Max Mean Mean Mean Coal (Thainguyen) 0.21 - 0.43 0.5 - 1.72 1 0.1 0.5- 2 6

0.30 1.43 0.32

Sandstone 2,5 3.5- 1 7 1.06 - 6.31 0.9 1.3- 2 5

(Thainguyen) 2.92 5.53 1.04

Coal 0.0 0.6- 3 6 0.41 - 103.93 0.2 1.2- 9 5

0.21 30.29 0.83

Sandstone 5 4. 1.6 - 1 2.63 - 10.01 0.72 - 1.23 Aleurolite Agrillte 2.27 4.67 1.01 (Quangninh)

Table 8

CORRELATION BETWEEN ASH CONTENT AND CONCENTRATION OF ELEMENTS IN QNB COAL AND CORRELATION BETWEEN SEVERAL OTHER ELEMENTS

CORRELATION DISCRIBED EQUATION CORRELATION RANGH AS E PARAMETERS COEFFICIENT "/lo h As , K , U,Th 9.68= h 0.131TU- As % 0.002H- 5.4K- 4 0.63 0-40

h As Sr , ,Y % Ash = 0.805Sr + 2.114Y - 15.426 0.89 0-50

U, K U = A •*• B.K 0.57 0-50

Th, U B.T+ A h U= 0.62 0-50

K, Th B.T+ A h K= 0.57 0-50

Z, U U = A + B.Zr 0.32 0-50

Pb, Th B.T+ Pb =A h 0.68 0-50

ü, Pb U = A + B.Pb 0.48 0-50

140 L Sample 92ISO

Irradiation: 20m. Cooling: €0h. Measurement: 600s

•irtir-

I

L« -J/S iW^»f»

b Sample 9217Q • ^ Irradiation. 2uh. Cooling 15d. Measurement 1800V s

FIG. 1. Gamma spectrogrammes of samples after irradiation on dalat nuclear reactor.

r t ' ' f>A • a

i* •H i j

s a ? »;

v_^——,—[•—jLP ( . Jü___

F/G. ;. (Com) Irradiation: Cooling:5m, Measurement:8m, 120s.

141 400 Numbe800 r of channe.l

400-

sandston, 5Q b Sampl1 92 ° eeN

»

y«*--*——k- 1600 2COO 0 "800 120C <0 JN'tUELbe f rhanruso r l

1600^ J

0 j o 3 CO1200J- c Sample N° 9243Q, Argillite

800-1 t-, o> D.

o o TifftWiti'i-\nruiuii IIIIT-T,

_ -0-+T 140C 1600 1800 2000 . o — •— — •> v ou bixNumbej f channeo r l

FIG. Gamma2. spectrogrammes of natural samples.

142 •UM "F* fi m« «S

er-

u

3 g

W

W

Si/ W W U'i™ Ml IM U U W""i M

143 ACKNOWLEDGEMENTS

This work was carried out under International Atomic Energy Agency sponsored Research contract No 6824/RB and No 6824/R1/RP o 1992-199durintw e th g 3 years.

REFERENCES

1/P. MATHEWJ .- Strea n O , m Coah AnalysiAs l s Basen o d Natural Gamma Ray Activity, IAEA-SM-308/89, Nuclear Techniques in Exploratio d Exploitationan Energf no Minerad yan l Resources, Pro f Symposiuo . m Vienna Jun8 5- ,e 1990. 2/ BRODA E., Schoufeld T. (1966) in "Technical Application of Radioactivity" Pergamon Press, 119-158

C BANGDA O 3,V / NGUYEN TRUNG TUAN, TRAN TRONGN VINHVA I ,PH THONG, Nuclea Analyzerh rAs , Insotopenpraxi 1 (1988)13 ) (3 , 4 2 s JINR-18-86-752 4/ VO DAC BANG, TRAN TRONG VINH, Electronic Aspect of the Low Cost Ash Monitor. Communications of the National Centre for Scientific Research p 40-44 , l ,l ,Vo 198 7 5/ MARAMATSU Y. et al, Simple Destructive Neutron Activation Analysis of Mercury and Selenium in Biological Material Using Activated Charcoal J. Radioanalytical and Nuclear Chem. 125, Nl. 175-181, 1988. 6/ SOWERB, NucleaD. . B Yr Technique Coae th l n i sIndustry , IAEA-SM-308/1, Nuclear Techniques in the Exploration and Exploitation of Energy and Mineral Resources, Proc. of a symp. Vienna Jun8 5- ,e 1990

144 LIST OF PARTICIPANTS

P. Arikan Ankara Nuclear Researc Trainind han g Centre Physics Department, X-ray Fluorescence Group Besevler - Ankara, Turkey

A. Abedinzadeh Radioisotope Dept, Nuclear Research Centre Atomic Energy Organizatio f Irano n P.O.BOX 11365-8486 Teheran, Iran

M. Borsaru CSIRO, Division of Geomechanics P.O.Bo . WaverleyMt , x54 , Victoria 3149, Australia

E. Chrusciel Institut f Physiceo Nuclead san r Techniques Academe Th f Mininyo Metallurgd gan y Dept Nucleaf o . r Geophysics Al. Mickiewicza 30 PL-30-059 Krakow, Poland

J. Loskiewicz Institute of Nuclear Research Dept f Applieo . d Nuclear Physics Ul. Radzikowskiego 152 PL-31-543 Krakow, Poland

. MilleM n CSIRO, Divisio f Minerano Procesd an l s Engineering Lucas Heights Research Laboratories, Private Mail Bag 7 Menai, NSW 2234, Australia

Vo Dac Bang Institute of Nuclear Technology Dept. of Nuclear Techniques Applications in Industry Viet Nam National Atomic Energy Commission, 59, Ly Thuong Kiet, Hanoi, Viet Nam

Yang Hongchang Coal Preparation Research Institute Central Coal Mining Research Institute Tangshan Branch, Xinhua Road Tangshan City, Hebei Province, China

R.S. Mani Division of Physical and Chemical Sciences (Scientific Secretary) International Atomic Energy Agency Wagramerstr , P.O.Bo5 . 0 x10 A-1400 Vienna, Austria

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